Part 2 / Book 6 — Book VI (continued 11)

A.D. 1815.—In the Philosophical Magazine (Vol. XLVI. pp. 161, 259), will be found an account of the electrical experiments of M. De Nelis, of Mechlin, or Malines, in the Netherlands, with an extension of them by George J. Singer and Andrew Crosse.

These allude to many investigations made during previous years by M. De Nelis, who reported upon them to Mr. Tilloch and to M. de la Méthérie, and which show “very remarkable and permanent evidence of the expansive power of the electric charge.” Singer adds: “It is difficult to contemplate such extraordinary mechanical effects without admitting that the power by which they are produced has at least the leading characteristics of a material substance.” At p. 127, Vol. XLVIII of the Phil. Mag., is an account of some further electrical experiments of M. De Nelis, one of which is intended to improve the simple current with an apparatus not insulated by discs. In this communication, which bears date July 10, 1815, he discourses upon the theory of the two fluids.

A.D. 1816.—Coxe (John Redman), M.D., Professor of Chemistry in the University of Pennsylvania, is the second to propose a system of transmitting signals, based, like Sömmering’s (A.D. 1809), upon the discovery of Nicholson and Carlisle.

In the first series of Dr. Thos. Thomson’s Annals of Philosophy for 1816 (not 1810), Vol. VII. pp. 162, 163, will be found Coxe’s letter “On the Use of Galvanism as a Telegraph,” wherein he says:

“I have contemplated this important agent as a probable means of establishing telegraphic communication with as much rapidity, and perhaps less expense, than any hitherto employed. I do not know how far experiment has determined galvanic action to be communicated by means of wires; but there is no reason to suppose it confined as to limits, certainly not as to time. Now, by means of apparatus fixed at certain distances, as telegraphic stations, by tubes for the decomposition of water, metallic salts, etc., regularly arranged, such a key might be adopted as would be requisite to communicate words, sentences or figures, from one station to another, and so on to the end of the line.... As it takes up little room, and may be fixed in private, it might in many cases of besieged towns, etc., convey useful intelligence with scarcely a chance of detection by the enemy. However fanciful in speculation, I have no doubt that, sooner or later, it will be rendered in useful practice. I have thus, my dear sir, ventured to encroach on your time with some crude ideas that may serve perhaps to elicit some useful experiments in the hands of others. When we consider what wonderful results have arisen from the first trifling experiments of the junction of a small piece of silver and zinc in so short a period, what may not be expected from the further extension of galvanic electricity? I have no doubt of its being the chief agent in the hands of nature in the mighty changes that occur around us. If metals are compound bodies, which I doubt not, will not this active principle combine their constituents in numerous places so as to explain their metallic formation; and if such constituents are in themselves aeriform, may not galvanism reasonably tend to explain the existence of metals in situations in which their specific gravities certainly do not entitle us to look for them?”

Coxe does not appear, however, to have at any time made satisfactory experiments, and his systems were considered impracticable until worked out by Alex. Bain during the year 1840.

At pp. 99–110, Vol. II of Dr. Coxe’s Emporium of Arts and Sciences, Philadelphia, 1812, will be found his illustrated “Description of a Revolving Telegraph,” for conveying intelligence by figures, letters, words or sentences, upon which plan, he says, he constructed a small telegraph that worked “readily and appropriately, although by no means fitted with the various pulleys, etc., to facilitate the motion of the ropes.”

References.—For full explanation of Coxe’s systems, see L. Turnbull, “Elect. Mag. Tel.” Highton’s “Electric Telegraph,” p. 39; Jour. Franklin Inst., Vol. XXI. for 1851, pp. 332, 333; Comptes Rendus for 1838, Vol. VII. pp. 593, etc.; Sci. Am. Supp., Nos. 404, p. 6446, and 453, p. 7234; Alfred Vail, “The American Electro-Magnetic Telegraph,” pp. 128, 129; Prime’s “Life of Morse,” p. 263.

A.D. 1816.—In Part I of the Philosophical Transactions for 1816, and at p. 14, Vol. XLVII of the Philosophical Magazine, will be seen an account of the observations and experiments made by Mr. John T. Todd on the torpedo off the Cape of Good Hope, during the year 1812 (“Abstracts of Papers ... Roy. Soc.,” Vol. II. p. 57).

It is said that the torpedo in this locality is never more than eight nor less than five inches in length, and never more than five nor less than three and a half inches in breadth. Mr. Todd found the columns of their electrical organs to be larger and less numerous in proportion than those described by Hunter, and that they appeared to be of a cylindrical form, while from a number of experiments he drew, among other conclusions, the fact that a more intimate relation exists between the nervous system and electrical organs of the torpedo, both as to structure and functions, than between the same and whatsoever organs of any known animal. (See Hunter at A.D. 1773.)

Reports of another series of experiments, carried on by Mr. Todd at La Rochelle during 1816, will be found in the Phil. Trans. for the year following as well as at p. 57, Vol. II of the “Abstracts of Papers ... of the Phil. Trans., 1800–1830.” The last-named investigations were made especially to determine whether the torpedo possessed any voluntary power over the electrical organs, either in exciting or interrupting their action, except through the nerves of these organs.

A.D. 1816.—Philip—Phillip—(Wilson), English physician, publishes in the Philosophical Transactions a continuation of researches made by him to establish the relations existing between the phenomena of life and voltaic electricity. Noad gives (“Manual,” pp. 341–344) an account of some of the experiments made on animals to prove the analogy existing between the galvanic energy and the nervous influence, and he alludes also to the fact of asthma having been relieved by galvanism through Dr. Philip, whose treatment had received the endorsement of Dr. Clarke Abel, of Brighton.

References.—Journal of Science, Vol. IX. See also Faraday’s “Experimental Researches,” 1791 and note; “Abstract of Papers ... Phil. Trans., 1800–1830,” Vol. II for 1822, p. 156.

A.D. 1816.—The Rev. James Bremmer, of the Shetland Islands, is rewarded by the Society of Arts for his night telegraph, the operation of which consists in the alternate exhibition and concealment of a torch in manner similar to that devised by Joachimus Fortius for Bishop Wilkins, as stated at A.D. 1641. This plan is said to have been successfully operated between the Copeland Island lighthouse and Port Patrick on the other side of the English Channel.

Particulars of the above-named night telegraph, as well as of the apparatus devised for day service, will be found in the Trans. of the Soc. of Arts, Vol. XXXIV. pp. 30, 213–227. The day telegraph consisted of a framework, having two circular openings, in each of which was a semicircular screen or shutter which, revolving upon an axis in the centre of the circle, was capable of assuming four different positions. This contrivance expressed an alphabet of sixteen letters, by dividing the latter into four classes of four each, and making one screen or shutter express the class, while the other indicated the number of the letter in that class.

A.D. 1816.—Sir Home Riggs Popham (1762–1820) British naval officer, who had been a rear-admiral in 1814, introduces his land semaphore which shows a great improvement upon all previous ones and at once replaces the Murray apparatus heretofore used by the English Admiralty (see A.D. 1795). It consists only of two arms placed upon the same hollow hexagonal mast, and movable upon separate pivots, each of which can be made to assume six different positions, giving together forty-eight different signals. It is fully described and illustrated at pp. 30, 167–177, Vol. XXXIV of the Trans. of the Soc. of Arts, and also appears in the “Telegraph” article, Vol. II of the “Encycl. of Useful Arts,” as well as at p. 149, Vol. XXIV of the “Penny Encycl.,” at pp. 67, 68, Vol. VIII of the (“Arts and Sciences”) “English Encycl.,” and in the “Telegraph” article by Sir John Barrow, one of the secretaries to the Admiralty, in the seventh “Britannica.”

In this same year (1816), Sir Home Popham also introduced a ship semaphore, which latter, as well as other similar devices of his construction, is to be found in the several publications already mentioned (the “Navy” article of the “Britannica” and pp. xii, xiii of Ronalds’ “Catalogue”).

A.D. 1816.—Ronalds (Francis), English experimentalist (1788–1873)—F.R.S., 1844, knighted 1870—whose serious attention to the development of electrical science appears to date from his meeting with M. De Luc in 1814, constructs at Hammersmith his telegraph which is the type of all dial instruments and which first presents the employment of two synchronous movements at the two stations. The telegraph is fully described and illustrated in the “Description of an Electrical Telegraph and of Some Other Electrical Apparatus,” 8vo, 83 pages, which Mr. Ronalds issued in pamphlet form, London, 1823, and which is said to be the first work published on electric telegraphy. Copious extracts from this are to be found at pp. viii-xi of the Ronalds “Catalogue,” and at pp. 129, 135–145, of Fahie’s “History,” the latter also containing several fine plates reproduced from the original work.

For his experimental line, Ronalds “erected two strong frames of wood at a distance of 20 yards from each other, and each containing 19 horizontal bars; to each bar he attached 37 hooks, and to the hooks were applied as many silken cords, which supported a small iron wire (by these means well insulated), which (making its inflections at the points of support) composed in one continuous length a distance of rather more than eight miles.” After making many experiments with this overhead line, he thus laid one underground:

“A trench was dug in the garden 525 feet in length, and four feet deep. In this was laid a trough of wood two inches square, well lined on the inside and out with pitch, and within this trough thick glass tubes were placed, through which the wire ran.”

His biographer, Mr. Frost, adds:

“In order to prevent the tubes from breaking by the variation of temperature, each length was laid a short distance from the next length, and the joint made with soft wax. The trough was then covered with pieces of wood, screwed upon it whilst the pitch was hot. They were also well covered with pitch, and the earth then thrown into the trench again.”

Mr. Edward Highton, at p. 40 of his work, the “Electric Telegraph,” 1852, says:

“Ronalds employed an ordinary electric machine and the pith-ball electrometer in the following manner. He placed two clocks at two stations; these two clocks had upon the second hand arbor a dial with twenty letters on it; a screen was placed in front of each of these dials, and an orifice was cut in each screen, so that only one letter at a time could be seen on the revolving dial. The clocks were made to go isochronously; and as the dials moved round the same letter always appeared through the orifices of each of these screens. The pith-ball electrometers were hung in front of the dials. The attention of the observer was called through the agency of an inflammable air gun fired by an electric spark.”

Realizing the value of his invention, Ronalds strove to bring it before the English Government, but was met (Aug. 5, 1816), with much the same encouragement we have seen vouchsafed Sharpe (A.D. 1813), and Wedgwood (A.D. 1814), viz. “Telegraphs of any kind are now wholly unnecessary and no other than the one now in use will be adopted.” The one alluded to was the semaphore line between London and Portsmouth, originally of the Chappe pattern and improved upon by Charles W. Pasley and Rear Admiral Popham.

Alluding to Mr. (afterward Sir) John Barrow’s letter in a note at p. 24 of his work Ronalds says:

“... Should they again become necessary, however, perhaps electricity and electricians may be indulged by his Lordship and Mr. Barrow with an opportunity of proving what they are capable of in this way.”

He was so disappointed that he not long after announced his “taking leave of a science which once afforded him a favourite source of amusement,” and that he was “compelled to bid a cordial adieu to electricity.” Fortunately for the scientific world, however, he afterward gave his attention again to electrical matters as is evidenced by many important papers contained in the publications noted below.

In Ronalds’ afore-named work the phenomenon of retardation of signals in buried wires is clearly foreseen and described, although Zetzsche endeavours to combat this assertion at p. 38 of his “Geschichte der Elektrischen Telegraphie,” Berlin, 1867. Speaking of the apprehended difficulty of keeping the wire charged with electricity, Ronalds suggests that when not at work “the machine be still kept in gentle motion to supply the loss of electricity by default of insulation; which default, perhaps, could not be avoided, because (be the atmosphere ever so dry, and the glass insulators ever so perfect), conductors are, I believe, robbed of their electricity by the same three processes by which Sir Humphry Davy and Mr. Leslie say that bodies are robbed of their sensible heat, viz. by radiation, by conduction, and by the motion of the particles of air.” He also gives descriptions of an improved electrical machine (eighth “Britannica,” Vol. VIII. p. 536; Sci. Am. Supp., No. 647, p. 10326; Noad’s “Manual,” p. 69), of a new method of electrical insulation and of some experiments on Vesuvius (Quarterly Jour. of Sci., Vols. II. p. 249; XIV. pp. 332–334), of a new electrograph for registering the charge of atmospheric electricity, of a pendulum doubler (Edin. Phil. Jour., Vol. IX, 1823, pp. 323–325) and of an attempt to apply M. De Luc’s electric column to the measurement of time. His other contributions relative to the dry pile are to be found in the Phil. Mag., Vols. XLIII. p. 414, and XLV. p. 466.

References.—“Biog. Mem. of Sir Francis Ronalds, F.R.S.,” by Alfred J. Frost, in Ronalds’ “Catalogue”; “Mem. of Dist. Men of Science,” by William Walker; Ronalds’ “Corres. and Memoir.,” in 1848–1849, to 1853, to April 17, 1855, to June 5, 1856, to Sept. 2, 1862, and in 1866–1870; Ronalds’ “Walk Through ... Exh. of 1855”; Illustrated London News of April 30, 1870; eighth “Britannica,” Vol. VIII. pp. 622, 627, for Ronalds’ improved electrometers and his telegraph; Nature, London, Nov. 23, 1871, Vol. V. p. 59; Journal of the Telegraph, March 15, 1875, Vol. VIII. p. 82, reporting the inaugural address of Mr. Latimer Clark before the English Society of Tel. Engineers; Comptes Rendus for 1838, Vol. VII. pp. 593, etc.; Sci. Am. Supp., No. 384, pp. 6, 127; No. 547, p. 8735, and No. 659, p. 10521, for his Telegraph; “Bombay Mag. Observatory,” 1850; Fortschrift des Phys., Vol. III. p. 586, and Buys-Ballot “Meteor. Preisfrage,” 1847, for Ronalds’ apparatus to measure atmospheric electricity; Phil. Mag., Vols. XLIV. p. 442; XLV. p. 261; XLVI. p. 203; and third series, Vols. XXVIII for 1846; XXXI. p. 191; British Ass. Reports for 1845, 1846, and Reports concerning the Kew Observatory for 1845, 1850, 1852; Phil. Trans. for 1847, Moigno’s Le Cosmos, Vol. XIII; L. Von Forster, “All. Bauzeitung” for 1848, p. 238; Noad’s “Manual,” pp. 184, 185, 748; Knight’s “Mechanical Dictionary,” Vol. I. p. 708; Turnbull’s “Electro-magnetic Telegraph,” p. 22; Annals of Electricity, Vol. III. p. 449; “English Cyclop.” (Arts and Sci.), Vol. VIII. pp. 71, 72; Jour. Soc. Teleg. Eng., 1879, Part XV, xxxviii; Vol. VIII, first part, p. 361; Reply to Mr. W. F. Cooke’s pamphlet, “The Elec. Teleg.: Was it Invented by Prof. Wheatstone?” London, 1855; Du Moncel, Vol. III; “Telegraphic Tales,” 1880, p. 42; J. D. Reid, “The Telegraph in America,” 1887, p. 71; Ure’s “Dict. of Arts,” etc., London, 1878, Vol. II (Elect. Metal.), p. 230; T. P. Schaffner, “Tel. Man.,” 1859, pp. 147–156; Silliman, “Principles of Physics,” 1869, p. 617; “Edin. Phil. Journal,” 1823, Vol. IX. pp. 322, 395.

A.D. 1816.—Porret (Robert) (1783–1868) communicates to the Annals of Philosophy (Vol. VIII. p. 74) a paper “On Two Curious Galvanic Experiments” (Electrovection, Voltaic Endosmose, or Electro-chemical Filtration).

He observed that when water was placed in a diaphragm apparatus, one side of which was connected with the positive and the other side with the negative electrode of the battery, that a considerable portion of the liquid was transferred from the positive toward the negative side of the arrangement. It has since been found that the same result occurs in a minor degree when saline solutions are electrolyzed, and, generally, the greater the resistance which the liquid offers to electrolysis the greater is the amount which is thus mechanically carried over.... It appears from the researches of Wiedemann (Pogg., Ann., Vol. LXXXVII. p. 321), which have been confirmed by those of Quincke, that the amount of liquid transferred, cæteris paribus, is proportioned to the strength or intensity of the current; that it is independent of the thickness of the diaphragm by which the two portions of liquid are separated; and that when different solutions are employed, the amount transferred in each case, by currents of equal intensity, is directly proportional to the specific resistance of the liquid. Miller, from whom the above is taken, says that this transfer has been minutely studied by Quincke, and gives an account of the latter’s work extracted from the Ann. de Chimie, LXIII. p. 479. Brewster’s allusion to Porret and Wiedemann (eighth “Britannica,” Vol. VIII. p. 630) is followed by the statement that Mr. Graham considers ordinary endosmose as produced by the electricity of chemical action.

References.—Graham, Vol. II. p. 266; De la Rive’s “Electricity,” Chap. IV. pp. 424–443; “Roy. Soc. Cat. of Sci. Papers,” Vol. IV. pp. 987, 988; Wm. Henry, “Elem. of Exp. Chem.” 1823, Vol. I. p. 178; C. Matteucci, “Traité des Phénom. Elect. Phys.,” 1844, p. 262 for Porret and Becquerel; Sturgeon’s “Sc. Researches,” Bury, 1850, p. 544; Poggendorff, Vol. II. p. 503; “Bibl. Britan.,” Vol. III, N.S., 1816, p. 15 (Thomson’s “Annals” for July 1816).

A.D. 1817.—Mr. J. Connolly makes known through an English and French pamphlet, entitled “An Essay on Universal Telegraphic Communication,” the details of his portable telegraph.

As shown in the thirty-sixth volume of the Transactions of the Society of Arts and in the twenty-fourth volume of the “Penny Cyclopædia,” his apparatus consists merely of three square boards painted with simple devices, like triangles, crescents, etc., the colours on the one side being the reverse of those on the other. Each of the six figures thus obtained is capable of producing four different distinct signals, making in all twenty-four, by successively turning each side of the board downward. In experiments made at Chatham, boards only eighteen inches square were found to answer for a distance of two miles, with a telescope having a magnifying power of twenty-five; and Mr. Connolly had also, it is said, exhibited these signals between Gros-nez and Sarque, a distance of seventeen miles, with boards twelve feet square.

At pp. 205, 208, of the Transactions of the Society of Arts, 1818, Vol. XXXV, and at p. 98, Vol. XXXVI for 1819, will be found Mr. Connolly’s system of telegraphing by means of flags in manner different from that of Lieut.-Col. John Macdonald alluded to at Pasley, A.D. 1808.

A.D. 1817.—In the “Encycl. Brit.” article treating of the influence of magnetism on chemical action, it is said that M. Muschman, Professor of Chemistry in the University of Christiania, made experiments to ascertain the effect of the earth’s magnetism on the precipitation of silver.

Desirous of explaining the chemical theory of the tree of Diana (Arbor Dianæ, first observed by Leméry), “he took a tube like a siphon and poured mercury into it, which accordingly occupied the lower part of the two branches; above the mercury he poured a strong solution of nitrate of silver. He then placed the two branches of the siphon so that the plane passing through them was in the magnetic meridian, and after standing a few seconds the silver began to precipitate itself with its natural lustre; but it accumulated particularly in the northern branch of the siphon, while that which was less copiously precipitated in the other branch had a less brilliant lustre, and was mixed with the mercurial salt deposited from the solution.” Muschman and Prof. Hansteen, having repeated this experiment with the same result, concluded that the magnetism of the earth had an influence on the precipitation of silver from a solution of its nitrate, and Muschman inferred from the experiment the identity of galvanism and magnetism (eighth “Britannica,” Vol. XIV. p. 42).

A.D. 1817.—Freycinet (Claude Louis Desaulses de) (1779–1842), captain in the French navy, is sent in command of an expedition fitted out by the French Government for the purpose of making scientific observations in a voyage round the world. The experimental stations were the Island of Rawak (near the coast of Guinea), Guam (one of the Ladrones), the Isle of France, Mowi (one of the Sandwich Islands), Rio Janeiro, Port Jackson, Cape of Good Hope, Paris and the Falkland Islands, as described in his “Voyage Autour du Monde ...” Paris, 1842.

His observations on the diurnal variations of the needle, which confirm the investigations made by Lieut.-Col. John Macdonald (A.D. 1808), are to be found at p. 54, Vol. XIV of the eighth “Britannica.”

References.—His “Voyage de Découvertes ... 1800–1804 ...” (F. Péron and Louis Freycinet), also his “Navigation et Géog. ...” 1815; the note at p. 158, Vol. I of Humboldt’s “Cosmos,” London, 1849; Phil. Mag., Vol. LVII. p. 20.

A.D. 1817.—In Vol. XLII. pp. 165, 166, of the Transactions of the Society of Arts will be found a record of the explanation of his magnetic guard for needle pointers which Mr. Westcott made before the Committee of Mechanics during the year 1817. This is said to consist of several “bar magnets smeared over with oil placed in a frame behind the grindstone.”

A.D. 1818.—Bostock (John) (1774–1846), English physician, F.R.S., lecturer at Guy’s Hospital, publishes in London his “Account of the History and Present State of Galvanism,” which is scarcely more than a compilation of works treating of that branch of science.

One of the passages is, however, worth quoting, for it reflects the opinion shared by many physicists of the time that the resources of the galvanic field were already wellnigh exhausted. It thus appears at p. 102: “Although it may be somewhat hazardous to form predictions respecting the progress of science, I may remark that the impulse which was given in the first instance by Galvani’s original experiments, was revived by Volta’s discovery of the pile, and was carried to the highest pitch by Sir H. Davy’s application of it to chemical decomposition, seems to have, in a great measure, subsided. It may be conjectured that we have carried the power of the instrument to the utmost extent of which it admits; and it does not appear that we are at present in the way of making any important additions to our knowledge of its effects, or of obtaining any new light upon the theory of its action.”

Bostock is also the author of “Outline of the History of the Galvanic Apparatus”; “On the Theory of Galvanism” (Nicholson’s Journal for 1802); “On the Hypothesis of Galvanism” (Annals of Philosophy, III, 1814), and of other works upon different scientific subjects. Reference is made by Mr. William Leithead (“Electricity,” London, 1837, Chap. VI. pp. 296, 297) to Bostock’s “Elementary System of Physiology,” 1827, Vol. II. pp. 413, etc., wherein is shown among other results, that, contrary to the views of Dr. Philip, there is no necessary connection between “the nervous influence” and the action of the glands. At p. 306 of Leithead appears another extract, from the third volume of Bostock, relative to the application of the electro-physiological theory in elucidating the phenomena of disease.

References.—Poggendorff, Vol. I. pp. 249, 250; “Nicholson’s Journal,” Vols. II. p. 296, and III. p. 3; Figuier, “Expos. et Histoire,” 1857, Vol. IV. p. 425; Gilbert, Vol. XII. p. 476.

A.D. 1819.—Hansteen (Christoph) (1784–1873), Norwegian astronomer and physicist, embodies in his notable work, “Untersuchungen über den Magnetismus der Erde ...” (“Inquiries regarding the magnetism of the earth”), the result of his extensive researches concerning terrestrial magnetism, the account of which is accompanied by a chart indicating the magnetic direction and dip at numerous places. This work, which is said to have been practically completed in 1813 (Humboldt, “Cosmos,” 1859, Vol. V. p. 66), was translated by the celebrated Peter Andreas Hansen (Poggendorff, Vol. I. pp. 1013–1015) from the original manuscript and published in German. It attracted much attention throughout the scientific world, and so highly was it thought of that in almost all the voyages of discovery afterwards undertaken most magnetic observations were made according to its directions.

Through the “Encyclopædia Britannica” we learn that Hansteen’s able work was first made known in England by Sir David Brewster through two articles in the Edin. Phil. Journal for 1820, Vol. III. p. 138, and Vol. IV. p. 114, and that an account of his subsequent researches, drawn up by Hansteen himself, appeared in the Edin. Journal of Science for 1826, Vol. V. p. 65. It is also stated that the Royal Society of Denmark proposed in 1811 the prize question, “Is the supposition of one magnetical axis sufficient to account for the magnetical phenomena of the earth, or are two necessary?” Prof. Hansteen’s attention had been previously drawn to this subject by seeing a terrestrial globe, on which was drawn an elliptical line round the south pole and marked Regio polaris magnetica, one of the foci being called Regio fortior, and the other Regio debilior. As this figure professed to be drawn by Wilcke, from the observations of Cooke and Furneaux, Hansteen was led to compare it with the facts; and the result of his researches was favourable to that part of Halley’s theory which assumes the existence of four poles and two magnetic axes. Hansteen’s Memoir, which was crowned by the Danish Society, forms the groundwork of his larger volume published in 1819. “In his fifth chapter, on the Mathematical Theory of the Magnet, he deduces the law of magnetic action from a series of experiments similar to those of Hauksbee and Lambert.... In determining the intensity of terrestrial magnetism Professor Hansteen observed that the time of vibration of a horizontal needle varied during the day. Graham had previously suspected a change of this kind, but his methods were not accurate enough to prove it. Hansteen found that the minimum intensity took place between ten and eleven a.m., and the maximum between four and five p.m. He concluded also that there was an annual variation, the intensity being considerably greater in winter near the perihelion, and in summer near the aphelion; that the greatest monthly variation was a maximum when the earth is in its perihelion or aphelion, and a minimum near the equinoxes; and that the greatest daily variation is least in winter and greatest in summer. He found also that the aurora borealis weakened the magnetic force, and that the magnetic intensity is always weakest when the moon crosses the equator.”

According to Dr. Whewell (“History of Induc. Sciences,” 1859, Vol. II. p. 226), the conclusions reached by Hansteen respecting the position of the four magnetic “poles” excited so much interest in his own country that the Norwegian Storthing, or Parliament, by a unanimous vote provided funds for a magnetic expedition which he was to conduct along the north of Europe and Asia, and this they did at the very time when, strange to say, they refused to make a grant to the King for building a palace at Christiania. The expedition was made in 1828–1830, and verified Hansteen’s anticipations as to the existence of a region of magnetic convergence in Siberia, which he considered as indicating a “pole” to the north of that country. The results were published in Hansteen and Due’s “Resultate magnetischer ...” (“Magn., Astron. and Méteor. Obs. on Journey through Siberia”) which appeared in 1863.

In the Sixth Dissertation, Chap. VII of the “Encycl. Brit.,” it is said that, next to Prof. Hansteen, science is mainly indebted for the great extension of our knowledge of the facts and the laws of terrestrial magnetism to two illustrious German philosophers, Baron Alexander von Humboldt and Prof. Karl Friedrich Gauss (1777–1855). An account is therein given of Gauss’s individual investigations, as well as of the researches he made in conjunction with Wilhelm Eduard Weber (1804–1891), who was likewise a professor at Göttingen. Of Alex. von Humboldt, we have spoken fully under date 1799, and of Gauss and Weber, mention has already been made at Schilling (A.D. 1812).

The very valuable contributions of Gauss and Weber appear throughout all the many scientific publications of the period, notably in the “Abhandlung d. Gött. Geselsch. d. Wiss.,” their joint work being shown to advantage in the important “Resultate ... des Magnet. Vereins,” published in Leipzig, 1837–1843.[58]

References.—For M. Hansteen’s scientific papers and for an account of additional magnetic results obtained by himself and others, consult the eighth “Britannica,” Vols. I. p. 745; IV. p. 249; XIV. pp. 15, 23, 42 (experiment with M. Muschman), 50, 55, 57–64, et seq., for Morlet and others; Thomson’s “Outline of the Sciences,” London, 1830, pp. 546–548; Whewell, “History of the Induc. Sci.,” Vol. II. pp. 613, 615, also p. 219 for Yates and Hansteen; Johnson’s new “Univer. Encycl.,” 1878, Vol. III. pp. 231–234 for Morlet, etc.: Weld’s “Hist. of Roy. Soc.,” Vol. II. p. 435; “Edin. Jour. of Sci.,” London, 1826, Vols. I. pp. 87, 334; V. pp. 65–71, 218–222; “Report of Seventh Meeting British Association,” London, 1838, Vol. VI. pp. 76, 82; J. G. Steinhauser’s articles published between 1803 and 1821; Harris’ “Rudimentary Magnetism,” London, 1852, Part. III. pp. 38, 39, 111; Phil. Mag., Vol. LIX. p. 248, and Phil. Mag. or Annals, Vol. II. p. 334; “Zeitschr. f. pop. Mitth.,” I. p. 33; Schweigger’s Journal, 1813–1827; Poggendorff’s Annalen, 1825–1855; “Académie Royale de Belgique” for 1853, 1855, 1865; C. Hansteen and C. Fearnley, “Die Univ.-Sternwarte ...” 1849; Hansteen, Lundh and Muschman, “Nyt. Mag. for Naturvid,” 1823–1856. See likewise his biography in the “English Cyclop. Supplement,” pp. 642, 643; “Catal. Roy. Soc. Sc. Pap.,” Vol. III. pp. 167–172; Vol. VI. p. 681, Vol. VII. p. 905; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 157; “Edin. Phil. Journal,” 1823, Vol. IX. p. 243; “Annual Rec. Sc. Disc.,” 1873, p. 683; 1875, p. 155; Knight’s “Amer. Mech. Dict.,” 1875, Vol. II. p. 1374, and eighth “Britan.,” Vol. XIV. p. 49, regarding Hansteen’s lines of no variation for 1787; Humboldt’s “Cosmos,” 1859, Vol. V. pp. 110–111, for the investigations of Hansteen, Sir Ed. Belcher and others, those of the last named being treated of at p. 493 of the Phil. Trans. for 1832; Noad, “Manual,” pp. 529, 530, 534, 616, 617, etc.; Appleton’s “New Am. Cycl.,” Vol. XI. p. 64.

A.D. 1819.—Hare (Robert) (1781–1858) who was for twenty-nine years Professor of Chemistry in the Pennsylvania University, publishes in Philadelphia “A New Theory of Galvanism, Supported by Some Experiments and Observations Made by Means of the Calorimotor ...” of which an English edition appears in London the same year. (A full review of this work is to be found more particularly at p. 206, Vol. LIV of the Philosophical Magazine; in the “Encycl. Metropol.,” Vol. IV (Galvanism), p. 222; in Ure’s “Dictionary of Chemistry,” Am. ed., article “Calorimotor”; at p. 187 of the Phil. Trans. for 1823; at pp. 409, 410, Vol. I of Gmelin’s “Chemistry,” and at pp. 413–423, Vol. I of Silliman’s Am. Jour. of Sci., the last named being accompanied by a very fine illustration of the Calorimotor.)

This apparatus, which has already been alluded to (Pepys, A.D. 1802), consists of sheets of zinc about 9 inches by 6, and of copper about 14 inches by 6, coiled around one another nearly half an inch apart; there being in all 80 coils, 2½ inches in diameter, which are let down by means of a lever into glass vessels containing the acid solution. Dr. Hare observes:

“Volta considered all galvanic apparatus as consisting of one or more electromotors, or movers of the electric fluid. To me it appeared that they were movers of both heat and electricity; the ratio of the quantity of the latter put in motion to the quantity of the former put in motion being as the number of the series to the superficies. Hence the word electromotor can only be applicable when the caloric becomes evanescent, and electricity almost the sole product, as in De Luc’s and Zamboni’s columns; and the word calorimotor ought to be used when electricity becomes evanescent and caloric appears the sole product.”

“It afterwards appeared quite natural,” remarks Mr. W. B. Taylor (Note B, “Mem. of Jos. Henry,” p. 376) “to distinguish these classes of effects by the old terms—‘intensity’ for electromotive force, and ‘quantity’ for calorimotive force. There is obviously a close analogy between these differences of condition and resultant, and the more strongly contrasted conditions of mechanical and chemical electricity; and indeed the whole may be said to lie in a continuous series, from the highest ‘intensity’ with minimum quantity, to the greatest ‘quantity’ with minimum intensity.”

Two years later (1821), Dr. Hare constructed his galvanic deflagrator. It consists of two pairs of troughs, each ten feet long, and containing 150 galvanic pairs, so arranged that the plates can all be simultaneously immersed into or withdrawn from the acid. Each pair turns on pivots made of iron, coated with brass or copper, and a communication is established between these and the voltaic series within by means of small strips of copper. The “Encycl. Brit.” gives a full description of the construction and working of the apparatus, as do also the “Encycl. Metropol.,” Vol. IV (Galv.), p. 176; Noad (“Manual,” pp. 266, 267); Gmelin (“Chemistry,” Vol. I. pp. 409, 410), and Silliman (“Journal of Sci. and Arts,” Vol. VII. p. 347). The first-named publication says of Dr. Hare’s deflagrator:

“A brilliant light, equal to that of the sun, was produced between charcoal points, and plumbago and charcoal were fused by Profs. Silliman and Griscom. By a series of 250, baryta was deflagrated, and a platina wire, three-sixteenths of an inch in thickness, ‘was made to flow like water.’ In the experiments with charcoal, the charcoal on the copper side had no appearance of fusion, but a crater-shaped cavity was formed within it, indicating that the charcoal was volatilized at this side and transferred to the other, where it was condensed and fused, the piece of charcoal at this pile being elongated considerably. This fused charcoal was four times denser than before fusion. In a letter from Prof. Silliman, which was transcribed in the Sc. Am. Sup. for Sept. 21, 1878, he says: ‘Undoubtedly the earliest exhibitions of electric light from the voltaic battery were those made with the deflagrators of Dr. Hare by Prof. Silliman at New Haven in 1822, and subsequently on a magnificent scale at Boston in 1834, when an arc of over five inches diameter was produced by the simultaneous immersion of 900 large-sized couples of Hare’s deflagrator. But no means had then been devised for the regulation of the electric light to render it constant, and although the writer as early as 1842 used this light successfully to produce daguerreotypes, the progress of invention had yet to make further use of the discovery of science before electrical illumination was possible.’”

The description of Dr. Hare’s electrical machine (before alluded to at Van Marum A.D. 1785), wherein the plate is mounted horizontally so as to show both negative and positive electricity, was published in London during 1823, and can be found in Vol. LXII of the Phil. Mag., as well as at pp. 538, 604, 605, Vol. VIII of the 1855 “Encycl. Brit.” In the last-named article mention is made of the introduction of a band (illustrated Fig. 7, Plate CCXXII) which prevents the plate from being cracked, as it frequently is, through some hasty effort to put it in motion while it adheres to the cushions. It is also therein stated that in order to offset the heavy expense attending the breakage of large cylinders and plates, M. Walkiers de St. Amand, of Brussels, among many others, made an apparatus of varnished silk 25 feet long and 5 feet wide, capable of giving sparks 15 inches long (see A.D. 1785), while Dr. Ingen-housz constructed machines with pasteboard discs four feet in diameter, soaked in copal or amber varnish dissolved in linseed oil, which gave sparks of one and even two feet in length.

In the fifth volume, new series, of the Amer. Phil. Trans. will be found Dr. Hare’s “Description of an Electrical Machine,” with a plate four feet in diameter, so constructed as to be above the operator; also of a battery discharger employed therewith, and some observations on the causes of the diversity in the length of the sparks erroneously distinguished by the terms positive and negative. Hare is also the inventor of a single gold-leaf electroscope of such great delicacy that it has, he says, enabled him to detect the electricity produced by one contact between a zinc and copper disc, each six inches in diameter (Noad, “Manual,” p. 29; Harris’ “Rudim. Elect.,” p. 50; Silliman’s Journal, Vol. XXXV). He invented several other electrical appliances, and he is likewise the author of numerous important memoirs which it would be impossible to detail in the narrow limits of this “Bibliographical History.” They will, however, be found recorded in the publications named below.

References.—Phil. Trans. for 1769, Vol. LXIX. p. 659. See also, for Walkiers de St. Amand, the entry at A.D. 1785, as well as Lichtenberg’s Magazin, Vol. III, 1st, p. 118, for the last-named year. To these might be added the machines made by Mundt, of silken strips (Gren’s Journal der Physik., Vol. VII. p. 319); by N. Rouland, “Descript. des mach, elec. à taffetas,” Amsterdam, 1785; by Croissant and Thore; of paper by W. H. Barlow (Phil. Mag., Vol. XXXVII. p. 428), of gutta percha; as well as machines of rubber by Fabre and Kunneman, as shown at Th. Du Moncel’s “Exposé des appl. de l’El.,” second ed., p. 399, and third ed., 1872, Vol. II. pp. 78, 122, 265, besides the peculiarly constructed machines of Erdmann Wolfram (Ferussac, “Bulletin des Sciences Tech.” for 1824); of G. H. Seiferheld, “Beschreib ... elektrische mach,” 1787; of F. E. Neuman, as modified by F. Zantedeschi (“Ann. Sci. Lom.-Ven.,” XII. p. 73), and of those described at p. 420, Vol. II, and at p. 4, Vol. III of Nicholson’s Magazine. Consult likewise, pp. 335, 340, second Am. ed. of the “New Edin. Encycl.,” 1817. Poggendorff, Vol. I. pp. 1018, 1019; “Cat. Sci. Papers of Roy. Soc.,” Vol. III. pp. 177–182; Vol. VI. p. 182; Silliman’s Am. Jour. Sci. and Arts, Vols. II. pp. 312, 326; III. p. 105; IV. p. 201; V. p. 94; VII. pp. 103, 108, 351; VIII. pp. 99, 145; X. p. 67; XII. p. 36; XIII. p. 322; XV. p. 271; XXIV. p. 253, XXV. p. 136; XXXI. p. 275; XXXII. pp. 272, 275–278, 280–285; XXXIII. p. 241; XXXV. p. 329; XXXVII. pp. 269, 383; XXXVIII. pp. 1, 336, 339; XXXIX. p. 108; XL. pp. 48, 303; XLI. p. 1, and XLIII. p. 291; Phil. Mag., Vols. LVII. p. 284; LXII. pp. 3, 8, etc.; Phil. Mag. or Annals, Vol. VI. pp. 114, 171; Journal of the Franklin Institute, third series. Vol. XV. pp. 188, etc.; Trans. of the Am. Phil. Soc., N.S., Vol. VI. p. 297 (for Hare and Allen) also pp. 339, 341, 343, and Vol. VII for 1841; “Mem. Jos. Henry,” Washington, 1880, p. 82; Figuier, “Exp. et Hist.,” 1857, Vol. IV. pp. 391, 401, 402; Dr. Thomas Thomson, “Outline of the Sc.,” London, 1830, pp. 515, 517; Appleton’s “New Amer. Cycl.,” Vol. VII. p. 66; Appleton’s “Dict. of Machines, Mechanics ...” 1861, pp. 432, 433; Dr. William Henry, “Elem. of Exper. Chem.,” London, 1823, Vol. I. p. 169, and Supplement, Chap. VII. p. 29; “Annual of Sc. Disc.” for 1862, p. 99.

A.D. 1819.—Gmelin (Leopold), the most distinguished member of the family of that name, publishes, at Frankfort, 1817–1819, the first edition of his celebrated “Handbuch d. theoret. Chemie,” which embodies the whole extent of chemical science as it then existed and the fourth and last edition of which, under the author’s supervision, appeared during 1843–1845. This extensive work is well known, both in its original form and through the very able translation of it made by Mr. Henry Watts. In the report of the Council of the Chemical Society for 1854, it is said that “the greatest service which Gmelin rendered to science—a service in which he surpassed all his predecessors and all his contemporaries—consists in this: that he collected and arranged in order all the facts that have been discovered in connection with chemistry. His Handbuch der theoret Chemie stands alone. Other writers on chemistry have indeed arranged large quantities of materials in systematic order, but for completeness and fidelity of collation and consecutiveness of arrangement, Gmelin’s Handbuch is unrivalled.”

Although many references have been made herein to Leopold Gmelin’s treatment of such departments of science as directly appeal to the readers of this compilation, it is well to mention some of the headings under which they are to be found. They are, “Electricity,” “Electro-chemical Theories,” “Electrolysis,” “Technical Apparatus of Electricity,” “Theory of Galvanism,” “Galvanic Batteries,” “Magnetic Condition of All Matter,” etc., etc., the whole occupying pp. 304 to 519, Vol. I of Gmelin’s English edition. The list of many of Leopold Gmelin’s valuable contributions to science is given in the “Catalogue Sc. Papers Roy. Soc.,” besides which may be mentioned his “Uber e angebl. meteorische masse” (Gilbert, Annalen, LXXIII for 1823), and his “Versuch einer elektro-chemisch. theorie” (Poggendorff’s Annalen der Physik und Chemie, Vol. XLIV for 1838, while at pp. 547–550 of Mr. J. J. Griffin’s able work, published in London during 1858, will be found the results obtained by Prof. G. Magnus and by Prof. Faraday with a summary of Gmelin’s conclusions under the heading of “The Evidence of Electrolysis in Favour of the Radical Theory.”

Gmelin Family

This family, which, through four generations, has been continuously distinguished for its valuable contributions to chemistry as well as to the natural and medical sciences, deserves equally well here of such a special mention as was accorded to the Bernoulli and Cassini families, under dates A.D. 1700 and 1782–1791.

Johann Georg Gmelin (1674–1728), a very able chemist and pharmaceutist of Tübingen, was the father of:

Johann Conrad Gmelin (1707–1759), physician and author in the same city of Tübingen.

Johann Georg Gmelin (1709–1755), distinguished naturalist and chemist, who graduated as M.D. in his nineteenth year, became a member of the St. Petersburg Acad. of Sc. and was sent by the Empress Anna, in company with G. A. Müller and other noted scientists, upon a ten years’ exploring expedition through Siberia. He was one of the first explorers of Northern Asia, and a genus of Asiatic plants was named Gmelina after him by Linnæus.

Philip Friedrich Gmelin (1722–1768), Professor of Botany and of Chemistry at Tübingen, author of many scientific monographs.

Samuel Gottlieb Gmelin (1744–1774), elder son of Philip Friedrich, who, like his uncle, graduated M.D. at nineteen and was sent two years later by the Empress Catherine II upon a scientific tour through South-Eastern Russia, is the author of “Historia Fucorum ...” as well as of other contributions which were edited through the famous Pallas. His biographical notice appears in the last volume of the “Reise durch Russland ...” published at St. Petersburg.

Johann Friedrich Gmelin (1748–1804), M.D., succeeded his father, Philip Friedrich, in the chair of chemistry and botany at the Tübingen University, became Professor of Medicine at Göttingen in 1778 and a member of “l’Académie des Curieux de la Nature.” He is the author of the thirteenth edition of Linnæus’ “Systema Naturæ,” which, notwithstanding Cuvier’s severe criticism of it, is said to be the only work which even professes to embrace all the objects of natural history described up to the year 1790 (“Encycl. Brit.,” 1855, Vol. IX. p. 4). He is also the author of “Geschichte der Chemie ...” Göttingen, 1797–1799, and of “Prælectio de col. metal. a Volta ...” (“Commentat. Soc. Gött.” XV (Phys.) for 1800–1803, p. 38). (See J. C. Poggendorff, “Biogr.-Literar. Handwörterbuch,” Vol. I. pp. 914–915.)

His son, Leopold Gmelin (1788–1853), who has already been noticed, practised chemical manipulation in the Tübingen pharmaceutical laboratory of Dr. Christian Gmelin, the son of Johann Conrad, and studied at Göttingen, Vienna and in Italy, after which he became medical and chemical professor at Heidelberg, 1817–1851 (Poggendorff, Vol. I. pp. 915–916).

Ferdinand Gottlob von Gmelin (1782–1848), elder son of Dr. Christian Gmelin, was Professor of Medicine and of Natural History in the Tübingen University, and wrote “Diss. sistens obs. phys. et chem. de electricitate et galvanismo” during 1802 (Poggendorff, Vol. I. pp. 916–917).

Christian Gottlob Gmelin (1792–1860), brother of the last named, M.D., was Professor of Chemistry and Pharmacy at the Tübingen University, and the author of “Experimenta electricitatem ...” 1820; “Uber d. Coagulat. ... d. Electricität” (Schweigger’s “Journal,” Vols. XXXVI for 1822); “Analyse d. turmalins ...” (Schweigger’s “Journal,” Vols. XXXI for 1821 and XXXVIII for 1823—Poggendorff’s “Annalen,” Vol. IX for 1827), as well as of a “Handbuch der Chemie,” published 1858–1861 (Poggendorff, Vol. I. p. 917; Phil. Mag. or Annals, Vol. III. p. 460).

References.—Gmelin and Schaub, “Effets Chimiques de la col. metal ...” (“Magas. Encyclop.,” Vol. VI. p. 201); Eberhard Gmelin’s letter to M. Privy Councillor Hoffmann of Mayence (1787), and his new investigations (1789) on the subject of animal magnetism (“Salzb. Med. Chir. Zeit.,” 1790, I. p. 358); Whewell, “Hist. of the Ind. Sc.,” 1859, Vol. II. p. 348.

A.D. 1819.—Dana (J. F.), M.D. (1793–1827), Chemical Assistant in Harvard University and Lecturer on Chemistry and Pharmacy in Dartmouth College, writes, Jan. 25, 1819, to Prof. Benjamin Silliman concerning his new form of portable electrical battery.

This apparatus, consisting of alternate plates of flat glass and of tinfoil, the sheets of which latter are connected together, is fully described at pp. 292–294, and is illustrated opposite p. 288, Vol. I of Silliman’s American Journal of Science, 1818, wherein it is stated that, while “in a battery of the common form, 2 feet long, 1 foot wide and 10 inches high, containing 18 coated jars, there will be no more than 3500 square inches of coated surface,” a battery of Dana’s construction will have no less than 8000 square inches covered with tinfoil, allowing the sheet of glass and of foil to be a quarter of an inch thick. In a brief description of this apparatus, which appears at p. 468, Vol. V of Tilloch’s Phil. Mag. and Journal, it is stated that a “battery constructed in this way contains, in the bulk of a quarto volume, a very powerful instrument; and when made of glass it is extremely easy, by varnishing the edges, to keep the whole of the inner surfaces from the air, and to retain it in a constant state of dry insulation.”

A.D. 1820.—Oersted—Örsted (Hans Christian), native of Denmark (1770–1851), Professor of Natural Philosophy and founder of the Polytechnic School in Copenhagen, makes known, through a small four-page pamphlet entitled “Experimenta circa effectum conflictus electrici in acum magneticam,” his great discovery of the intimate relation existing between electricity and magnetism (Thomson’s Annals of Philosophy for October 1820, Vol. XVI, first series, pp. 273–276). He thus lays the foundation of the science of electro-magnetism, which subsequently was so materially developed by Ampère and Faraday.

It is said that after taking his doctor’s degree in 1799, he gave much attention to galvanism, and that in the year 1800 he made important discoveries as to the action of acids during the production of galvanic electricity. He was one of the earliest to show the opposite conditions of the poles of the galvanic battery, also that acids and alkalies are produced in proportion as they neutralize each other. Upon his return from a trip to France and Germany, 1801–3, he lectured on electricity and the cognate sciences, publishing thereon a number of essays. (These are to be found, more particularly, in J. H. Voigt’s Magazin, Vol. III. p. 412; Van Mons’ Journal, No. IV. p. 68; the Bulletin of the Société Philomathique, No. LXVII. an. xi. p. 128; A. F. Gehlen’s Neues Allgem. Journal d. Chemie, Vols. III for 1804, VI for 1806, VIII for 1808; Schweigger’s Journal, Vol. XX; Phil. Mag., Vol. XXIII. p. 129; the “Skand. Lit.-Selskabs Skrifter,” Vol. I; “Oversigt over det Kongl. ... Forhandlinger,” 1814–1815; “Nyt Biblioth. f. Physik,” etc., Vol. IX, and in the Journal de Physique as well as in the Journal du Galvanisme.)

He revisited Germany during 1812, and, at the suggestion of Karsten Niebuhr, published in Berlin his work “Ansicht der Chemischen Naturgesetze. ...” (“Inquiry into the identity of chemical and electric forces”), a translation of which was made by M. P. Marcel T. de Serres under the title of “Recherches sur l’Identité. ...” (Fahie, “Hist. of Electric Teleg.,” 1884, pp. 270–273). The last-named work appeared at Paris during 1813, and not, as stated at p. 41, Vol. LVII of the Philosophical Magazine, during 1807, which was the date of the original small German edition.[59]

One of his biographers says that Oersted was lecturing one day to a class of advanced students, when, as a means of testing the soundness of the theory which he had long been meditating, it occurred to him to place a magnetic needle under the influence of a wire uniting the ends of a voltaic battery in a state of activity. “In galvanism,” said he, “the force is more latent than in electricity, and, still more so in magnetism than in galvanism; it is necessary therefore to try whether electricity, in its latent state, will not affect the magnetic needle.” He tried the experiment upon the spot and found that the needle tended to turn at right angles to the wire, thus proving the existence of electro-magnetism, or the relation of electricity and magnetism as mutually productive of each other, and as evidences of a common source of power. Previous to this time the identity of magnetism and electricity had only been suspected. For several months Oersted prosecuted experiments on the subject, and on the 21st of July 1820 promulgated his discovery through the Latin pamphlet above alluded to. Therein he contends that there is always a magnetic circulation around the electric conductor, and that the electric current in accordance with a certain law always exercises determined and similar impressions on the direction of the magnetic needle, even when it does not pass through the needle but near it (the eighth edition of the “Encycl. Britannica,” Fifth Dissertation, pp. 739, 740, 745; and the Sixth Dissertation, pp. 973–976; Schaffner, “Tel. Manual,” 1859, Chap. VIII; Practical Mechanic, Glasgow, 1842, Vol. III. p. 45).

For this discovery, which naturally excited the wonder of the entire scientific world, he received the Copley medal of the English Royal Society, the Dannebrog order of knighthood and numerous testimonials from nearly every quarter of Europe. As observed by Mr. J. D. Forbes (Sixth Disser. “Encycl. Brit.,” Vol. I), “the desideratum of a clear expression of the manifest alliance between electricity and magnetism has been so long and so universally felt that the discovery placed its author in the first rank of scientific men.... The prize of the French Institute, which had been awarded to Davy for his galvanic discoveries, was bestowed upon Oersted.”

Oersted’s experiments were repeated before the French Academy of Sciences by M. De la Rive on Sept. 11, 1820, and, seven days later, as we shall see, Ampère made known the law governing electro-magnetism (Mme. Le Breton, “Hist. et. Appl. de l’Elect.,” Paris, 1884, pp. 72, 73; W. Sturgeon, “Sci. Researches,” Bury, 1850, p. 18; Higg’s Translation of Fontaine’s “Electric Lighting,” London, 1878, p. 54).

The many investigations subsequently carried on by Oersted in different branches of sciences are alluded to in the works named below. Perhaps the most interesting, outside of the ones already spoken of, are those attaching to thermo-electricity which he made in conjunction with Baron Fourier, and independently of Dr. Seebeck.

References.—Eighth “Britannica,” pp. 651 and 652, Vol. XXI, as well as pp. 11 and 12, Vol. XIV of Oersted’s “Efterretning om nogle nye, af Fourier og Oersted ...” Kiobenhaven, 1822–1823, translated into French as mentioned in Vol. XXII of the Annales de Chimie et de Physique; “Oversigt over det Kongl. ...” for 1822–1823 and 1823–1824; Poggendorff, Vol. III. pp. 309–312; “Catal. Sci. Papers Roy. Soc.,” Vol. I. pp. 697–701; Biog. Sketch by P. L. Möller, “Oersted’s Character und Leben,” 1851, also Hauch und Forchammer, 1853; Obituary notice in Jour. Frankl. Inst., 1851, Vol. XXI. p. 358; Humboldt, “Cosmos,” 1849, Vol. I. pp. 182, 185 and the 1819–1820 entry of “Magnetic Observations,” in Vol. V; “Oversigt over det Kongl. danske Videnskabernes Selskabs Fordhandlinger” for 1822, 1832, 1834–1835, 1836–1837, 1840–1842, 1847–1849; Poggendorff’s Annalen, Vol. LIII; “Ursin’s Magaz. f. Kunstnere ...” Vols. I and II; “Dict. of Electromagn.,” 1819; Sturgeon’s Annals of Electricity, Vol. I. p. 121; Hatchett “On the Experim. ... of Oersted and Ampère” (Phil. Mag., Vol. LVII. p. 40), Phil. Mag., Vols. LVI. p. 394; LVII. pp. 47–49; LIX. p. 462; Phil. Mag. or Annals, Vol. VIII. p. 230; Annales de Chimie for Aug. 1820, p. 244; S. S. Eyck, “Over de magnetische ...” (Bibl. Univ., 1821); Translation by H. Sebald, of H. C. Oersted’s “Leben,” 1853; Michaud, “Biog. Univ.,” Vol. XXXI. p. 196; P. L. Möller, “Der Geist in der Natur” (”The Spirit in Nature”); Elie de Beaumont, “Memoir of Oersted” (“Smith. Rep.” for 1863); Gilbert’s Annalen, Vol. LXVI. p. 295, 1820; Callisen, “Medicinisches Schriftseller-Lexikon”; W. Sturgeon’s “Sci. Researches,” Bury, 1850, p. 8 (for 1807), and pp. 9–12 for English version of Oersted’s pamphlet which was translated in German in Vol. XXIX of Schweigger’s “Journal,” as well as in Vol. LXVI of Gilbert’s Annalen, and which appeared in French in Vol. XIV of the Annales de Chimie et de Physique for 1820, as well as in Vol. II. pp. 1–6 of “Collection de Mémoires relatifs à la Physique,” Paris, 1885. See also “Biogr. Gén.,” Vol. XXXVIII. pp. 522–535; “Göttinger Gelehrte Anz.,” No. 171; Sturgeon’s “Sc. Researches,” pp. 17, 18, 28, 415; Thomson’s “Annals of Philosophy,” Vol. XVI. p. 375 for second series of observations; Van Marum on “Franklin’s Theory of Electricity,” pp. 440–453; “Galvanism,” by Mr. John Murray, p. 467; “Note sur les expériences ... de Oersted, Ampère, Arago, et Biot,” (Annales des Mines, 1820); L. Turnbull, “Elec. Mag. Tel.,” 1853, pp. 45, 221; J. F. W. Herschel’s “Preliminary Discourse,” 1855, pp. 244, 255; Fahie, “Hist. Elec. Tel.,” 1884, pp. 270–275, Harris, “Rud. Elec.,” 1853, p. 171; Ostwald’s Klassiker, No. 63 and “Elektrochemie,” 1896, p. 67; Mrs. Somerville, “Con. of Phys. Sci.,” 1846, p. 314; Noad, “Manual,” p. 642; “Lib. Useful Know.” (El Magn.), pp. 4, 79; Lardner’s “Lectures,” 1859, Vol. II. p. 119; Tomlinson’s “Cycl. Useful Arts,” Vol. I. p. 559; Ure’s “Dict. of Arts,” 1878, Vol. II. p. 233; Henry Martin’s article in Johnson’s “New Cyclopædia,” 1877, Vol. I. pp. 1512, 1514; “Nyt Biblioth. f. Physik,” Band I auch Scherer’s Nord. Arch., II; “Tidskrift f. Natur ...” I 1822: Schumacher’s “Astron. Jahrbuch” for 1838; L. Magrini, “Nuovo metodo ...” Padova, 1836; Boisgeraud “On the Action of the Voltaic Pile ...” (Phil. Mag., Vol. LVII. p. 203); Sci. Am. Suppl., No. 454, p. 7241; Schweigger’s Journal, Vols. XXXII, XXXIII, LII; Figuier, “Expos. et Hist.,” 1857, Vol. IV. p. 393; “Engl. Cycl.,” “Arts and Sci.,” Vol. III. p. 782; Brande’s “Man. of Chem.,” London, 1848, Vol. I. p. 248; Prime’s “Life of Morse,” pp. 264, 451; Dr. Henry’s “Elm. of Exper. Chem.,” London, 1823, Vol. I. pp. 193–203; Jour. of the Frankl. Inst. for 1851, Vol. XXI. p. 403; “La Lumière Electrique” for Mar. 19, 1887, p. 593, and for Oct. 31, 1891, pp. 201, etc.: Sir William Thomson, “Math. Papers,” reprint, etc., 1872; “Encyl. Metrop.” (Elect. Mag.,); G. B. Prescott, “Elect. and the El. Tel.,” 1885, Vol. I. p. 91; “Smithsonian Report” for 1878, pp. 272, 273, note; Bacelli (L. G.), “Risultati ...” Milano, 1821; “Bibl. Britan.,” Vol. XVII, N.S. p. 181; Vol. XVIII, N.S. p. 3; “Edin. Phil. Journal,” Vol. X. p. 203; “Journal of the Soc. of Tel. Eng.,” 1876, Vol. V. pp. 459–464, for a verbatim copy of Oersted’s original communication on his discovery of electro-magnetism, and pp. 464–469 for a translation thereof by the Rev. J. E. Kempe under the title of “Experiments on the effect of electrical action on the Magnetic Needle.” For the interesting electro-magnetic experiments of J. Tatum, at this same period, consult the Phil. Mag., Vol. LVII, 1821, p. 446; Vol. LXI, 1823, p. 241; Vol. LXII, 1823, p. 107, and, for additional investigation, the Vols. XLVII and LI for years 1816 and 1818.

A.D. 1820.—On Oct. 9, M. Boisgeraud, Jr., reads, before the French Académie des Sciences, a paper concerning many of his experiments, which prove to be merely variations of those previously made by Oersted.

He observed that connecting wires, or arcs, placed anywhere in the battery, affect the needle, and he noticed the difference of intensity in the effects produced when electrical conductors are employed to complete the circuit. He proposed to ascertain the conducting power of different substances by placing them in one of the arcs, cells or divisions of the battery, and bringing the magnetic needle, or Ampère’s galvanometer, toward another arc, viz. to the wire or other connecting body used to complete the circuit in the battery. With regard to the positions of the needle and wire, as observed by Boisgeraud, they are all confirmatory of Prof. Oersted’s statement (“Ency. Met.” (Electro.-Mag.), Vol. IV. p. 6).

One month later, Nov. 9, 1820, Boisgeraud reads, before the same Académie, his paper “On the Action of the Voltaic Pile upon the Magnetic Needle,” which will be found on pp. 203–206 and 257, 258, Vol. LVII of the Philosophical Magazine.

A.D. 1820.—Banks (Sir Joseph) (1743–1820), a very eminent English naturalist and traveller, to whom reference has been made under the A.D. 1775 date, deserves mention here were it alone for the fact that while occupying the presidential chair of the Roy. Soc., during the extraordinary long and unequalled period of over forty-two years (1777, date of Sir John Pringle’s retirement, to 1820, the date of President Banks’ death) he was instrumental in bringing prominently before the world many of the most important discoveries and experiments known in the annals of magnetism and electricity.

Sir Joseph Banks was succeeded in the presidency of the Royal Society by William Hyde Wollaston, M.D., June 29, 1820, and by Sir Humphry Davy, Bart., Nov. 30, 1820, the last named holding the office seven years (R. Weld, “Hist. Roy. Soc.,” 1848, Vol. II. p. 359). Banks and Dr. Solander, the pupil of Linnæus, had sailed (1768–1771) with Captain Cook in his voyage around the globe, in the capacity of naturalists, and afterwards (1772) visited Iceland, where they made many important discoveries. In 1781 Banks was created a baronet; he received the Order of the Bath in 1795 and subsequently had many honours conferred upon him by different English and foreign societies. It is said that he was never known to be appealed to in vain by men of science, either for pecuniary assistance or for the use of his extensive library.

References.—Tilloch’s Phil. Mag. for 1820, Vol. LVI. pp. 40–46; “Cat. Sci. Papers Roy. Soc.,” Vol. I. p. 176; Dr. Thomas Thomson, “Hist. Roy. Soc.,” London, 1812, p. 12; Gentleman’s Magazine for 1771, 1772 and 1820; “Biog. Univ.,” Vol. LVII, Suppl. p. 101; Larousse, “Dict. Univ.,” Vol. II. p. 155; “Eloge Historique de Mr. J. Banks, lu à la Séance de l’Académie Royale des Sciences, le 2 Avril 1821”; Sir Everard Home, “Hunterian Oration,” Feb. 14, 1822. See besides, the Phil. Mag., Vol. LVI. pp. 161–174, 241–257, for “A review of some of the leading points in the official character and proceedings of the late President of the Royal Society,” contrasting the respective personal merits and achievements of Sir John Pringle and of Sir Joseph Banks; “Lives of Men of Letters and Science,” by Henry, Lord Brougham, Philad., 1846, pp. 199–229, 294–295.

A.D. 1820.—Barlow (Peter), F.R.S. (1776–1827), who taught mathematics at the Military Academy of Woolwich from 1806 to 1847, brings out the first edition of his “Essay on Magnetic Attractions, Particularly as Respects the Deviation of the Compass on Shipboard Occasioned by the Local Influence of the Guns, etc., with an Easy Practical Method of Observing the Same in all Parts of the World.” One of his biographers states that through this valuable publication, which received the Parliamentary reward from the then existing Board of Longitude, as well as presents from the Russian Emperor, he was the first to reduce to strictly mathematical principles the method of compensating compass errors in vessels (Edin. Jour. of Sci., London, 1826, Vols. I. pp. 181, 182; II. p. 379).

This work contains the results of the many experiments to ascertain the influence of spherical and other masses of iron upon the needle, which Barlow instituted, more particularly after Prof. Hansteen’s investigations became generally known. Sir David Brewster details Barlow’s work in the “Encycl. Brit.,” and refers to the separate observations of Mr. Wm. Wales (at A.D. 1774), Mr. Downie (at A.D. 1790), Captain Flinders (at A.D. 1801), and Charles Bonnycastle (at A.D. 1820), mentioning the fact that it is to Mr. W. Bain we owe the distinct establishment and explanation of the source of error in the compass arising from the attraction of all the iron on board of ships. The small 140-page book which Mr. Bain published on the subject in 1817 is entitled “An Essay on the Variation of the Compass, Showing how Far it is Influenced by a Change in the Direction of the Ship’s Head, with an Exposition of the Dangers Arising to Navigators from not Allowing for this Change of Variation.” Brewster remarks that additional light was thrown upon Mr. Bain’s observations by Captains Ross, Parry and Sabine, but that we owe to Prof. Barlow alone a series of brilliant experiments which terminated in his invention of the neutralizing plate for correcting in perfect manner this source of error in the compass (Noad’s “Manual,” pp. 531, 532; Olmstead’s “Introduct. to Nat. Hist.,” 1835, pp. 206, 210). The simple contrivance therein alluded to is described and illustrated at pp. 9 and 90–91 of the “Britannica,” article on “Navigation,” and may briefly be said to consist of only a thin circular plate of iron placed in a vertical position immediately behind the binnacle or compass (Fifth Dissertation of “Britannica,” Vol. I. p. 745, and article “Seamanship,” in Vol. XX. p. 27). Such plates were immediately tried in all parts of the world and were at once applied to the English vessels “Conway,” “Leven” and “Barracouta” (Trans. Soc. of Arts for 1821, Vol. XXXIX. pp. 76–100; Harris’ “Rud. Mag.,” III. pp. 69–76; John Farrar, “Elem. of El. ...” 1826, pp. 376–383; Westminster Review for April 1825; “Encycl. Metropol.,” Vol. III (Magnetism), pp. 743, 799).

For Mr. Barlow’s experiments on the influence of rotation upon magnetic and non-magnetic bodies, the result of which was communicated by him to the Royal Society, April, 14, 1825, six days before the receipt of S. H. Christie’s paper “On the Magnetism of Iron, Arising from its Rotation,” communicated by J. F. W. Herschel, see pp. 10, 33, 34, of the “Britannica,” Vol. XIV above referred to (Edin. Jour. of Science, 1826, Vols. III. p. 372, and V. p. 214. Consult also, J. Farrar, “Elem. of El.,” 1826, pp. 387–395. For his extensive observations regarding the influence of heat on magnetism and relative to the variation, as well as for the mode of constructing his artificial magnets, consult the same volume of the “Britannica,” at pp. 35, 36, 50–53 et seq. and p. 73. See likewise, for the variation, Dr. Thomas Thomson’s “Outline of the Sciences,” London, 1830, pp. 549–556; Harris, “Rud. Mag.,” I, II. pp. 152–153. For Samuel Hunter Christie, consult “Abstracts of Papers ... Roy. Soc.,” Vol. II. pp. 197, 225, 243, 251, 270, 305, 321, 347 and 351).

The new variation chart which Prof. Barlow constructed and in which he embraced the magnetic observations made in 1832 by Sir James Ross, R.N., is described and illustrated in Phil. Trans. for 1833, pp. 667–675, Plates XVII, XVIII. He remarks that the very spot where his officer found the needle perpendicular, “that is, the pole itself, is precisely that point in my globe and chart in which, by supposing all the lines to meet, the several curves would best preserve their unity of character, both separately and conjointly as a system” (eighth “Britan.,” Vol. XIV, note, p. 50; Noad, “Manual,” p. 617; D. Olmstead, “Intr. to Nat. Phil.,” 1835, p. 192).

Mr. Barlow’s electro-magnetic globe was exhibited by Dr. Birkbeck in his lectures on “Electro-Magnetism” at the London Institution, May 26, 1824. (Its construction is fully described, more particularly, at p. 65 of the English “Encycl. Brit.” (Magnetism); p. 91 of the “Lib. of Useful Knowledge” (Electro-Magnetism); pp. 139–140, Vol. I of the Edin. Jour. of Science, London, 1826, and pp. 120–122, Part III of Harris’ “Rud. Mag.”) Its purpose was to show that what had hitherto been considered as the magnetism of the earth might be only modified electricity, and it was also intended to illustrate the theory advanced by M. Ampère, who, as is well known, attributed all magnetic phenomena to electric currents. In the words of Dr. Brewster:

“Barlow considers it as probable that magnetism as a distinct quality has no existence in Nature. As all the phenomena of terrestrial magnetism can be explained on the supposition that the magnetic power resides on its surface, it occurred to Mr. Barlow that if he could distribute over the surface of an artificial globe a series of galvanic currents in such a way that their tangential power should everywhere give a corresponding direction to the needle, this globe would exhibit, while under electrical induction, all the magnetic phenomena of the earth upon a needle freely suspended above it. Mr. Barlow says ‘he has proved the existence of a force competent to produce all the phenomena without the aid of any body usually called magnetic,’ yet he acknowledges that ‘we have no idea how such a system of currents can have existence on the earth, because, to produce them, we have been obliged to employ a particular arrangement of metals, acids, and conductors.’”

Barlow was the first to test the practicability of Ampère’s suggestion that by sending the galvanic current through long wires connecting two distant stations, the deflections of enclosed magnetic needles would constitute very simple and efficient signals for an instantaneous telegraph (Ann. de Chimie et de Phys., 1820, Vol. XV. pp. 72, 73). He has thus stated the result: “In a very early stage of electro-magnetic experiments, it had been suggested (by Laplace, Ampère and others) that an instantaneous telegraph might be established by means of conducting wires and compasses. The details of this contrivance are so obvious, and the principle on which it is founded so well understood, that there was only one question which could render the result doubtful; and this was, is there any diminution of effect by lengthening the conducting wires? It had been said that the electric fluid from a common (tinfoil) electric battery had been transmitted through a wire four miles in length without any sensible diminution of effect, and, to every appearance, instantaneously; and if this should be found to be the case with the galvanic circuit, then no question could be entertained of the practicability and utility of the suggestion above adverted to. I was therefore induced to make the trial; but I found such a sensible diminution with only 200 feet of wire, as at once to convince me of the impracticability of the scheme. It led me, however, to an inquiry as to the cause of the diminution, and the laws by which it is governed.” This passage is quoted in “Smithsonian Report” for 1878, p. 279; Fahie, “Hist. El. Tel.,” p. 306; “Memor. of Jos. Henry,” 1880, pp. 223, 224, the last named containing the following footnote: “On the Laws of Electro-Magnetic Action,” Edinburgh Philosophical Journal, Jan., 1825, Vol. XII. pp. 105–113:

“In explanation and justification of this discouraging judgment from so high an authority in magnetics, it must be remembered that both in the galvanometer and in the electro-magnet, the coil best calculated to produce large effects was that of least resistance; which unfortunately was not that best adapted to a long circuit. On the other hand the most efficient magnet or galvanometer was not found to be improved in result by increasing the number of galvanic elements. Barlow in his inquiry as to the law of diminution was led (erroneously) to regard the resistance of the conducting wire as increasing in the ratio of the square root of its length” (pp. 110, 111 of the last-cited “Journal.)”]

Mr. Taylor justly adds that subsequent experiments have proved Ohm’s law (announced three years after Barlow’s) of a simple ratio of resistance to length as approximately correct.

References.—G. B. Prescott, “The Speaking Telephone,” 1879, II; Sci. Am. Supp., Nos. 405, p. 6466; 453, p. 7235; 547, p. 8735: “Mem. of Jos. Henry,” 1880, pp. 83, 94, 144, 485, 487. See also, Poggendorff, Vol. I. pp. 102, 103; Whewell, “Hist. Ind. Sciences,” 1859, Vol. II. pp. 223, 224, 245, 254, 616; “Lib. Useful Knowledge” (Magnetism), p. 86 and (El. Mag.), pp. 7, 18, 22, 28; Sturgeon’s “Sci. Researches,” Bury, 1850, pp. 26, 29, 31, 298; Humboldt, “Cosmos,” 1849, Vol. I. p. 183; Mrs. Somerville, “On the Earth not a Real Magnet,” in the “Conn. of the Phys. Sci.,”; Phil. Mag., Vols. LV. p. 446; LX. pp. 241, 343; LXII. p. 321; Harris, “Rud. Mag.,” Part III. pp. 114–116; “Encycl. Metropol.,” Vol. IV (Elect. Mag.), pp. 1–40; “Abstracts of papers ... Roy. Soc.,” Vol. II. pp. 164, 197, 241, 318; “Cat. Sc. Papers ... Roy. Soc.,” Vol. I. pp. 182–184; “Bibl. Britan.,” Vol. XX, N.S. p. 127; “Edin. Phil. Journal,” 1824, Vol. X. p. 184 (alludes to papers of Barlow and Christie in Phil. Trans. for 1823, Part II).

Mr. Wm. Henry Barlow, second son of Peter Barlow, is the author of a treatise, “On the spontaneous electrical currents observed in the wires of the electric telegraph,” which was published in London during 1849 and appeared in Part I of the Phil. Trans., for that year. He is also the inventor of a new electrical machine alluded to herein at Hare (A.D. 1819), also at p. 130 of the “Annual of Sc. Disc.,” at pp. 76–77 of Noad’s “Manual,” and at p. 428, Vol. XXXVII of the “Philosophical Magazine.”

A.D. 1820.—Laplace (Pierre Simon, Marquis de) (1749–1827), a very distinguished French astronomer and mathematician, suggests for telegraphic purposes the employment of magnetic needles suspended in multipliers of wire, in place of the voltameters of Sömmering, and on the 2nd of October 1820 his theory is thus explained by Ampère in a paper read before the French Academy of Sciences:

“According to the success of the experiment to which Laplace drew my attention, one could, by means of as many pairs of live wires and magnetic needles as there are letters of the alphabet, and by placing each letter on a separate needle, establish, by the aid of a distant pile, and which could be made to communicate by its two extremities with those of each pair of conductors, a sort of telegraph, which would be capable of indicating all the details that one would wish to transmit through any number of obstacles to a distant observer. By adapting to the battery a keyboard whose keys were each marked with the same letters and establishing connection (with the various wires) by their depression, this means of correspondence could be established with great facility, and would only occupy the time necessary for pressing down the keys at the one station and to read off the letters from the deflected needles at the other.”

Laplace is, perhaps, best known by his “Traité de Mécanique Céleste,” the sixteen books and supplements to which are by many considered, next to Newton’s “Principia,” the greatest of astronomical works; a book which has been truly said to have had no predecessor and which has been called the crowning glory of Laplace’s scientific career. His next important work was the “Théorie Analytique des Probabilités,” the most mathematically profound treatise on the subject which had yet appeared, while his “Système du Monde” was called by Arago “one of the most perfect monuments of the French language.” By Prof. Nichols, Laplace is called “the titanic geometer”; by Mr. Airy “the greatest mathematician of the past age”; by Prof. Forbes “a sort of exemplar or type of the highest class of mathematical natural philosophers of this, or rather the immediately preceding age.”

Laplace also wrote, in conjunction with Lavoisier, a treatise “On the Electricity which Bodies Absorb when Reduced to Vapor” (Mém. de Paris for 1781). Prof. Denison Olmstead, treating of the origin of atmospherical electricity (“Introd. to Nat. Phil.,” 1835, pp. 158, 159), says: “Among the known sources of this agent none seems so probable as the evaporation and condensation of watery vapor. We have the authority of two of the most able and accurate philosophers, Lavoisier and Laplace, for stating that bodies in passing from the solid or liquid state to that of vapor, and, conversely, in returning from the aeriform condition to the liquid or solid state, give unequivocal signs of either positive or negative electricity,” and he adds, in a footnote:

“M. Pouillet has lately published a set of experiments, which seems to overturn Volta’s theory of the evolution of electricity by evaporation. He has shown that no electricity is evolved by evaporation unless some chemical combination takes place at the same time ...” (Thomson, “Outlines,” p. 440) ... “But we shall be slow to reject the results of experiments performed by such experimenters as Lavoisier and Laplace, especially when confirmed by the testimony of Volta and Saussure.”

With regard to the origin of meteorites, Laplace has advanced the very bold theory that they may be products of Lunar volcanoes, and Prof. Lockhart Muirhead stated that he would “present the reasoning upon which this extraordinary hypothesis is founded in the popular and perspicuous language of Dr. Hutton, of Woolwich: the respect due to the name of Laplace justifying the length of the extract,” which he gives at pp. 633–635, Vol. XIV of the 1857 “Britannica.”

References.—Humboldt, “Cosmos,” London, 1849, Vol. I. pp. 108–109; Young, “Course of Lectures,” London, 1807, Vol. II. p. 501, alluding to “Zach. Mon. Corr.,” VI. p. 276, also to Gilbert, XIII. p. 353, 108, and stating that Olbers had suggested Laplace’s idea in 1795. See “Mem. of the Astronom. Soc. of London,” Vol. III. p. 395: Laplace, “Mem. de l’Institut” for 1809, p. 332; Dr. Young’s “Course of Lectures,” 1807, Vol. I. pp. 249, 250, 522; Vol. II. p. 466; Humboldt, “Cosmos,” London, 1849, Vol. I. pp. 28, 76, 130; Vol. II. p. 712; Lavoisier at A.D. 1781: Biot at A.D. 1803; Annal. de Ch. et Phys., Vol. XV. pp. 72, 73, and for Laplace and Lavoisier, see Delaunay, “Manuel ...” 1809, p. 178; “Mem. de l’Acad. des Sc.,” for 1781; “Journal des Savants,” for Feb. 1850 and Nov. 1887; Houzeau et Lancaster, “Bibl. Gén.,” Vol. II. p. 184; “Cat. Sc. Pap. Roy. Soc.,” Vol. III. pp. 845–848; Johnson’s “Cyclopædia,” pp. 1647–1650 and the “First Supplement,” p. 62.

For Laplace and Joseph Louis Lagrange, see “Mémoires de l’Institut,” Vol. III. p. 22; also “Pioneers of Science,” by Sir Oliver Lodge, London, 1905, Lecture XI, and for Lagrange, consult “Journal des Savants,” Sept. 1844, May 1869, August 1878, Sept. 1879, Sept. 1888 and Oct. 1892.

M. Cyrille Pierre Théodore Laplace, captain in the French navy, is the author of the “Voyage Autour du Monde ... sur la Corvette Favorite ...” and of “Campagne de Circumnavigation de la Frégate l’Artémise ...” published in Paris during the years 1833, 1839 and 1841.

Baron Jean Baptiste Fourier, celebrated French physicist (1768–1830) who, in 1827, succeeded Laplace as head of the Council of the Ecole Polytechnique (“Biog. Gén.,” Vol. XVIII. p. 346) says of his predecessor:

“Posterity, which has so many particulars to forget, will little care whether Laplace was for a short time minister of a great state. The eternal truths which he has discovered, the immutable laws of the stability of the world, are of importance, and not the rank which he occupied” (C. R. Weld, “Hist. Roy. Soc.,” Vol. II. p. 465). Fourier is the author of “Expériences thermo-électriques” (“Encycl. Brit.,” ninth ed., Vol. IX. p. 490; “Eng. Cycl.,” Biography, Vol. II. p. 977).

A.D. 1820.—Dutrochet (René Joachim Henri) (1776–1847) a distinguished French natural philosopher, and likewise medical adviser to the King of Spain, Joseph Bonaparte, publishes an interesting treatise on meteors, in conjunction with Mr. Nathaniel Bowditch, who had already written many very able papers on astronomical subjects and who afterwards translated the “Mécanique Céleste” of Laplace. Eight years later (1828) appeared Dutrochet’s “Nouvelles Recherches ...” wherein he attributes to electricity the direction taken by fluids through animal and vegetable membranes. The passage of a fluid from without inwardly he called endosmosis, and the passage of the fluid from within outwardly he termed exosmosis.

Of Dutrochet, Dr. John Hutton Balfour, of Edinburgh, makes mention when treating of the temperature of plants. He thus expresses himself: “While the nutritive processes are going on in the plant, there is a certain amount of heat produced. This, however, is speedily carried away by evaporation and other causes, and it is not easily rendered evident. Dutrochet, by means of Becquerel’s thermo-electric needle, showed an evolution of heat in plants. In doing this, he prevented evaporation by putting the plant in a moist atmosphere. In these circumstances the temperature of the active vegetating parts, the roots, the leaves, and the young shoots, indicated a temperature above the air of ½ to ¾ of a degree Fahrenheit. Van Beek and Bergsma, in their experiments on the Hyacinthus Orientalis and the Entelea Arborescens, found the proper heat of the active parts of plants about 1·8° F. above that of the air. The vital or proper heat of plants, according to Dutrochet, is found chiefly in the green plants, and it undergoes a quotidian paroxysm, reaching the maximum during the day, and the minimum during the night. When stems become hard and ligneous, they lose this vital heat. Large green cotyledons gave indications of a proper heat. The hour of quotidian maximum varied from 10 a. m. to 3 p. m. in different plants.”

It is stated by Becquerel that in the act of vegetation, the earth acquires continually an excess of positive electricity, while the bark and part of the wood receive an excess of negative electricity. The leaves act like the green part of the parenchyma of the bark—that is to say, the sap which circulates in their tissues is negative with relation to the wood, to the pith, and to the earth, and positive with regard to the cambium. The electric effects observed in vegetables are due to chemico-vital action, and he asserts that the opposite electric states of vegetables and of the earth give reason to think that, from the enormous vegetation in certain parts of the globe, they must exert some influence on the electric phenomena of the atmosphere.

References.—Gmelin’s “Chemistry,” Vol. I. p. 447; “Biog. Gén.,” Vol. XV. p. 506; Poggendorff, “Annalen,” Vol. I. p. 663; Larousse, “Dict. Univ.,” Vol. VI. p. 1448; J. W. Ritter, in “Denkschr. d. Münch. Acad.” for 1814, and the eighth ed. of the “Ency. Brit.” Vol. XXI. p. 635, for observations concerning the mimosa pudica and the mimosa sensitiva; “Cat. Sc. Papers Roy. Soc.,” Vol. II. pp. 422–425; Vol. VI. p. 646; Vol. VII. p. 584; Poggendorff, Vol. I. p. 633; “Observations on the diurnal variation of the magnetic needle,” in Sturgeon’s “Annals,” Vol. VII. pp. 369–370, and in the Comptes Rendus, Vol. XII. p. 298, of Feb. 8, 1841; Burnet, “On the motion of sap in plants. Researches of Dutrochet on Endosmose and Exosmose ...” London, 1829 (“Phil. Mag. or Annals,” Vol. V. p. 389).

A.D. 1820.—Fresnel (Augustin Jean) (1788–1827), one of the most distinguished French mathematicians and natural philosophers, communicates a paper detailing his experiments for decomposing water by means of a magnet. He produced a current in an electro-magnetic helix enclosing a bar-magnet covered with silk, and on plunging the ends of the wire in water he observed some very remarkable effects which are set forth in the Annales de Chimie et de Phys., series 2, Vol. XV. p. 219.

References.—“Eloge de Fresnel,” by Arago, in his “Œuvres,” Vol. I; Account of Fresnel’s life in the “Biog. Univ.;” Whewell, “Hist. of Induc. Sci.,” 1859, Vol. II. pp. 96, 102, 114–117; “Œuvres complètes d’Augustin Fresnel, publiées par les soins du Ministre de l’Instruction Publique,” Paris, 1870, in three vols.

A.D. 1820.—Sir Richard Phillips (1778–1851), communicates, July 11, to the Philosophical Magazine (Vol. LVI. pp. 195–200) a very interesting paper entitled “Electricity and Galvanism Explained on the Mechanical Theory of Matter and Motion.” After reviewing the then existing theories, he concludes by saying:

“Electricity is no exception to the mechanical principles of matter and motion, and in regard to the kindred phenomena of galvanism, I will content myself with observing that it is merely accelerated electricity, the interposing fluid being palpably decomposed and evolving the electrical powers, each term in the series of plates being a new impulse or power added to the previous one, till the ultimate effect is accelerated, like that of a body falling by the continuous impulses of the earth’s motions, or like a nail heated red-hot by accelerations of atomic motion produced by repeated percussions of a hammer.”

Consult “Bibl. Ital.,” Vol. XXVII. p. 107 for references to the “Annals of Philosophy,” in which he mentions an experiment upon a young poplar, “whereby it would seem that copper was imbibed in the branches, etc., from a solution placed at its roots, and that it was precipitated on a knife used to cut off a branch.”

A.D. 1820.—Brewster (Sir David) (1781–1868), a very distinguished English natural philosopher and writer, who had just founded the “Edinburgh Philosophical Journal” in conjunction with Prof. Robert Jameson, announces his discovery of the existence of two poles of greatest cold on opposite sides of the northern pole of the earth. By this he was, like other authors, led to the belief that there might be some connection between the magnetic poles and those of maximum cold, and he remarks (Noad “Manual,” London, 1859, p. 545, and article “Magnetism” in “Encycl. Brit.”): “Imperfect as the analogy is between the isothermal and magnetic centres, it is yet too important to be passed over without notice. Their local coincidence is sufficiently remarkable, and it would be to overstep the limits of philosophical caution to maintain that they have no other connection but that of accidental locality; and if we had as many measures of the mean temperature as we have of the variation of the needle, we might determine whether the isothermal poles were fixed or movable.” Similar opinions entertained by Dr. Dalton, Dr. Traill and Mr. Christie are also mentioned by Noad, who quotes from Oersted’s treatise on “Thermo-Electricity” the statement of the Danish philosopher “that the most efficacious excitation of electricity upon the earth appears to be produced by the sun, causing daily evaporation, deoxidation and heat, all of which excite electrical currents.”

From his able paper in the Edinburgh Philosophical Transactions for 1820, one is led to share Sir David Brewster’s belief “that two meridians of greatest heat and two of greatest cold are called into play, and that the magnetism of our globe depends in great measure upon electro or rather thermo-magnetic currents.” The electro-magnetic hypothesis was, he says, ably supported by Prof. Barlow in his paper “On the probable electric origin of all the phenomena of terrestrial magnetism,” communicated to the Phil. Trans. for 1831. Brewster thus locates the two poles of maximum cold: The American pole in N. Lat. 73, and W. Long. 100 from Greenwich, a little to the East of Cape Walker; the Asiatic pole in N. Lat. 73 and E. Long. 80, between Siberia and Cape Matzol, on the Gulf of Oby. Hence the two warm meridians will be in W. Long. 10 and E. Long. 170, and the two cold meridians in W. Long. 100 and E. Long. 80.

As has already been indicated (under A.D. 1717, Leméry), Sir David Brewster was the discoverer of the pyro-electrical condition of the diamond, the garnet, the amethyst, etc. His development of some of Haüy’s experiments led to a similar discovery, attaching to several mineral salts as well as to the plates and powders of the tourmaline, of the scolezite and the melozite; and he likewise experimented with the boracite, mesotype and with the several minerals and artificial crystals detailed at pp. 208–215, Vol. I of the Edin. Jour. of Science, London, 1826; and in Chap. II. s. 1, vol. viii of the eighth “Encycl. Brit.,” article on “Electricity.”

At Part I. chap. i. s. 6 of the last-named article will be found Brewster’s observations on the nature and origin of electrical light, his latest researches having been made, like those of Joseph von Fraunhofer (see A.D. 1814–1815), on the dark and on the luminous lines which appear in the spectrum formed from it by a prism.

During the year 1831 appeared Brewster’s “Treatise on Optics,” his “Life of Sir Isaac Newton,” and his “Letters on Natural Magic.” It is in one of the chapters of the last-named work that he treats of automatic talking machines and remarks: “We have no doubt that before another century is completed a talking and a singing machine will be numbered among the conquests of science.”

Brewster’s other scientific treatises are too numerous and cover too wide a range to be enumerated here. The “Catal. of Sci. Papers of the Roy. Soc.” (Vol. I. pp. 612–623) gives the titles of as many as 299 contributions made by him on important subjects, and he has had no less than 76 papers in the first 39 parts of the North British Review, 30 in the Phil. Trans. and 28 in the Edin. Review. They appear, in fact, in all the prominent publications of his time, and have won for him leading honours, more especially from the Edinburgh and Aberdeen Universities and the Scotch, Irish, English and French Societies, the French Academy of Sciences doing him the signal honour of selecting him as one of its eight foreign associates in place of Berzelius, deceased. Conjointly with Davy, Herschel and Charles Babbage, he originated the British Association during 1831, and it was in this same year that he was knighted and decorated by King William IV. He had been made a Fellow of the Royal Society of Edinburgh in 1808, and had during the same year undertaken the editorship of the “Edinburgh Encyclopædia of Sci., Lit. and Art.” This he continued for twenty-two years, after which he edited the Edin. Jour. of Sci., and also entered with Taylor and Phillips upon the editorship of the London and Edin. Phil. Mag. and Journal. Many of our readers will doubtless be glad to know that the last named was a continuation of the well-known Philosophical Magazine so often quoted in this “Bibliographical History.”

References.—The obituary notice contributed by Dr. J. H. Gladstone to the proceedings of the Royal Society; Chemical News, Amer. reprint, Vol. II. pp. 198, 233; also p. 293 for accounts given by Sir J. Simpson and Prof. Fraser; J. Robison and Brewster, “A System of Mechan. Phil.,” London and Edin., 1822; Ferguson and Brewster’s “Essays and Treatises on Astr. Elect.,” etc., Edinburgh, 1823; Brewster’s several articles in the “Encycl. Britannica,” 7th and 8th editions, on “Electricity and Magnetism”; Transactions of the Roy. Soc. of Edinburgh, Vols. IX. 1821; XX. Part IV; Edin. Jour. of Sci., Oct. 1824, No. 2, p. 213; Noad, “Manual,” London, 1859, pp. 31, 32, 636–638; Harris, “Magnetism,” Part III. p. 119; Whewell, “Hist. of Induc. Sci.,” 1859, Vol. II. pp. 75, 81, 331, 332; the lectures delivered by Wm. A. Miller during 1867 before the Royal Institution of Great Britain.

Charles Babbage (1792–1871), a prominent English scientist who is mentioned above and who besides being one of the founders of the Royal Astronomical Society, as has already been stated, was also a founder of the British Association and the originator of the Statistical Society, is the author of valuable papers, exhibiting a wide range of learning and research—mainly on mathematical subjects and relating to magnetical and electrical phenomena—which have been published in the Reports of the Royal and other Societies (“English Cycl.,” Vol. I. p. 457; “Encyl. Brit.,” ninth ed., Vol. III. p. 178; Larousse, “Dict.,” Vol. II. pp. 5–6; account of Babbage’s work in C. R. Weld’s “Hist. Roy. Soc.,” Vol. II. pp. 369–391).

A.D. 1820.—Fisher (George) (1794–1873), who two years before had joined Captain David Buchan in his voyage to the Arctic regions, is the first to point out the true cause of the sudden alteration in the rates of chronometers at sea. “He observed,” says Dr. Roget, “that the chronometers on board the ‘Dorothea’ and ‘Trent’ had a different rate of going from that they had on shore, even when these vessels had been frozen in, and therefore when their motion could not have contributed to that variation; ... this effect could be attributed only to the magnetic action exerted by the iron in the ships upon the inner rim of the balance of the chronometers, which is made of steel. A similar influence was perceptible on placing magnets in the neighbourhood of the chronometers. This conclusion was confirmed by experiments made for this purpose by Mr. Barlow, who ascertained that masses of iron devoid of all permanent magnetism occasioned an alteration in the rates of chronometers placed in different positions in their vicinity.”

References.—Fisher’s article “On the Errors in Longitude as Determined by Chronometers at Sea, Arising from the Action of the Iron in the Ships upon the Chronometers,” communicated by John Barrow, F.R.S., to the Phil. Mag., Vol. LVII. pp. 249–257. See besides, Edinburgh Jour. Sci., London, 1826, Vol. V. p. 224; Phil. Trans. for 1820, Part. II. p. 196, and the volume for 1833, relative to magnetical experiments; also the “Lib. U. K.” (Magn.), p. 63. For Capt. Buchan, consult Barrow’s “Chronological History of Voyages into the Arctic Regions.”

Mr. George Thomas Fischer (1722–1848) is the author of “A Practical Treatise on Medical Electricity” (Poggendorff, Vol. I. p. 756).

A.D. 1820.—Bonnycastle (Charles), Professor of Mathematics in the University of Virginia, treats of the distribution of the magnetic fluids in masses of iron, as well as of the deviations which they produce in compasses placed within their influence, at pp. 446–456, Vol. LV of Tilloch’s Philosophical Magazine.

He refers to the then recent publication of Peter Barlow’s “Essay on Magnetic Attractions,” containing the results of many experiments, made principally upon spheres of iron, as well as to Dr. Young’s views of the subject, which were printed by order of the Board of Longitude, and he says that the principle upon which he intends establishing his inquiry “is an extension of the law that regulates the action of electrified bodies upon conductors; which was first given by M. Poisson in the Memoirs of the Institute for 1811, and employed by him to determine the development of the electric fluids in spheres that mutually act on each other.”

The afore-named dissertation, at the time, called forth a rejoinder from a correspondent and a further communication from Mr. Bonnycastle, both of which appear at pp. 346–350, Vol. LVI of the same publication.

References.—Silliman’s Journal, Vol. XL. p. 32; “Sketch of the Life of Chas. Bonnycastle,” by Thomas Thomson; Poggendorff, Vol. I. pp. 234, 235; article “Magnetism,” p. 9, Vol. XIV of the eighth “Britannica.”

A.D. 1820.—Harris (Wm. Snow), member of the College of Surgeons, and a very distinguished English scientist (1791–1867), proposes to the Board of the Admiralty his system of lightning conductors, of which an account appears at p. 231, Vol. LX of the Phil. Mag., as well as in a separate work published at London during 1822. This is followed by his “Observations on the Effects of Lightning ...” 1823, and by papers relative to the defence of ships and buildings from lightning, which were published, more particularly, in several numbers of the Nautical Magazine, the Phil. Mag., the Annals of Electricity, and in the Proc. Lond. Elec. Soc. for 1842, as well as in his “Record of Phil. Papers,” and under separate heads during many years between 1827 and 1854. One of his biographers remarks:

“His researches have gone far to remove certain popular errors as to what have been called ‘conductors’ and ‘non-conductors’ of electricity, and to show the inutility of the old form of lightning rod in the majority of cases; it being necessary, in place of such rod form, to link into one great chain all the metallic bodies employed in the construction of a building, thus providing a connection with these conductors between the highest parts and the ground, the single conductor, in one highest part, being possibly insufficient to divert the course of the fluid and protect the whole fabric. These general principles have been largely applied to the protection of the ships of the Royal Navy during the last five and twenty years, under his advice and direction; and, laying aside the opinions which had been commonly received, the masts themselves of a ship have all been rendered perfectly conducting by incorporating with the spars capacious plates of copper, whilst all the large metallic masses in the hull have been tied, as it were, into a general conducting chain, communicating with the great conducting channels in the masts, and with the sea. This may be considered as the greatest experiment ever made by any country in the employment of metallic conductors for ships, and the result has been to secure the navy from a destructive agent, and to throw new light upon an interesting department of science” (Whewell, “Hist. of Induc. Sci.,” Vol. II. pp. 199, 200; Phil. Mag. for March 1841; eighth “Encycl. Britannica,” Vols. VIII. pp. 535, 610, 611, and XX. p. 24; “Edin. Review” for Oct. 1844, Vol. LXXX. pp. 444–473).

Harris was the first, says Brewster, who introduced accurate quantitative measures into the investigation of the laws of statical electricity—the unit measure by which quantity is minutely estimated—and also the hydro-electrometer and scale-beam balance by which its intensity and the laws of attractive forces at all distances are demonstrated. Of not less value is the thermo-electrometer, by which the heating effects of given quantities of electricity are measured and rendered comparable with the varying conditions of quantity and intensity. Besides these instruments, we owe to Harris the discovery of a new reactive force, through which repulsion and other small physical forces are investigated and determined by means of his bifilar balance, founded upon the reactive force of two vertically suspended parallel threads when twined upon each other at a given angle, and acted upon by a suspended weight. With the aid of these instruments he has carried on a variety of important inquiries into the laws of electrical forces, and the laws and operations of electrical accumulation (eighth “Brit.,” Vol. VIII. p. 535). His papers on the subject appeared in 1825 and 1828, and a résumé of them is given by Noad (“Manual” 1859, pp. 35, 137–140), as well as in the “Electricity” article of the “Britannica,” both of which contain descriptions and illustrations of Harris’ unit jar and electro-thermometer.