ADDITIONAL NOTES

Referred to by figures in the text.

The Horologe of Flora is alluded to by Pliny with his usual felicity of thought and expression. “Dedi tibi herbas horarum indices; et ut ne sole quidem oculos tuos a terra avoces, heliotropium ac lupinum circumaguntur cum illo. Cur etiam altius spectas, ipsumque cœlum scrutatis? Habes ante pedes tuos ecce Vergilias.”--Hist. Nat. lib. xviii. c. 27.

Linnæus enumerates forty-six flowers which possess this kind of sensibility. The following are a few of them, with their respective hours of rising and setting, as the Swedish naturalist terms them. He divides them into meteoric flowers, which less accurately observe the hour of unfolding, but are expanded sooner or later, according to the cloudiness, moisture, or pressure of the atmosphere.

2nd. Tropical flowers, which open in the morning, and close before evening every day; but the hour of the expanding becomes earlier or later, as the length of the day increases or decreases.

3rd. Equinoctial flowers, which serve for the construction of Flora’s dial, since they open at a certain and exact hour of the day, and for the most part close at another determinate hour: for instance, the Leontodon Taraxacum, dandelion, opens at 5-6, closes at 8-9; Hieracium Pilosella, mouse-ear hawkweed, opens at 8, closes at 2; Tragopogon pratensis, yellow goat’s-beard, opens at sunrise, and shuts at noon with such regularity, that the husbandman who adopts it as the signal of dinner-time need not fear to have his pudding too much or too little boiled; Sonchus lævis, smooth sow-thistle, opens at 5, closes at 11-12; Lactuca sativa, cultivated lettuce, opens at 7, closes at 10; Tragopogon luteus, yellow goat’s-beard, opens at 3-5, closes at 9-10; Lapsana, nipplewort, opens at 5-6, closes at 10-11; Nymphæaalba, white water-lily, opens at 7, closes at 5; Papaver nudicaule, naked poppy, opens at 5, closes at 7; Hemerocallis fulva, tawny day-lily, opens at 5, closes at 7-8; Convolvulus, opens at 5-6; Malva, mallow, opens at 9-10, closes at l; Arenaria purpurea, purple sandwort, opens at 9-10, closes at 2-3; Anagallis, pimpernel, opens at 7-8; Portulaca hortensis, garden purslain, opens at 9-10, closes at 11-12; Dianthus prolifer, proliferous pink, opens at 8, closes at 1; Cichoreum, succory, opens at 4-5; Hypocharis, opens at 6-7, closes at 4-5; Crepis, opens at 4-5, closes at 10-11; Picris, opens at 4-5, closes at 12; Calendula Africana, opens at 7, closes at 3-4, &c.

“Thus in each flower and simple bell,

That in our path betrodden lie,

Are sweet remembrancers who tell

How fast the winged moments fly.”

In like manner may be formed a calendar of Flora: thus, if we consider the time of putting forth leaves, the honeysuckle protrudes them in the month of January; the gooseberry, currant and elder, in the end of February, or beginning of April; the oak and ash in the beginning, or towards the middle of May, &c.

It may, perhaps, be asked how this decrease of weight could have been ascertained; since, if the body under examination decreased in weight, the weight which was opposed to it in the opposite scale must also have diminished in the same proportion; for instance, that if the lump of lead lost two pounds, the body which served to balance it must also have lost the same weight, and therefore that the different force of gravity could not be detected by such means. It is undoubtedly true that the experiment in question could not have been performed with an ordinary pair of scales, but by using a spiral spring it was easy to compare the force of the lead’s gravity at the surface of the earth, and at four miles high, by the relative degree of compression which it sustained in those different situations. We may take this opportunity of observing, that as the force of gravity varies directly as the mass, or quantity of matter, a body weighing a pound on our earth would, if transferred to the sun, weigh 27-3/4 pounds; if to Jupiter, 3-1/10 pounds; if to Saturn, 1-1/9; but, if to the moon, more than three ounces.

With respect to the effect of the centrifugal force as alluded to in the text, it may be here observed, that it has been found by calculation that, at the equator, the diminution of gravity occasioned by the centrifugal force arising from the rotation of the earth, amounts to about the 289th part. But since this number is the square of 17, it follows, that, if our globe turned more than 17 times faster about her axis, or performed the diurnal revolution within the space of 84 minutes, the centrifugal force would predominate over the powers of gravitation, and all the fluid and loose matters would, near the equinoctial boundary, have been projected from the surface. On such a supposition the waters of the ocean must have been drained off, and an impassable zone of sterility interposed between the opposite hemispheres. By a similar calculation, combined with that decreasing force of gravity at great distances from the centre, it may be inferred, that the altitude of our atmosphere could never exceed 26,000 miles. Beyond this limit, the equatorial portion of air would have been shot into indefinite space. If it were possible to fire off a cannon ball with a velocity of five miles in a second, and the resistance of the air could be taken away, it would for ever wheel round the earth, instead of falling upon it; and supposing the velocity to reach the rate of seven miles in a second, the ball would fly off from the earth, and be never heard of more.

It is scarcely possible so to strain the imagination as to conceive the velocity with which light travels. “What mere assertion will make any man believe,” asks Sir W. Herschel, “that in one second of time, in one beat of the pendulum of a clock, a ray of light travels over 192,000 miles, and would therefore perform the tour of the world in about the same time that it requires to wink with our eyelids, and in much less than a swift runner occupies in taking a single stride?” Were a cannon ball shot directly towards the sun, and it were to maintain its full speed, it would be twenty years in reaching it, and yet light travels through this space in seven or eight minutes.

In order to perform this experiment with the highest degree of accuracy, a body of considerable specific gravity should be selected, such as lead or iron; for a common stone experiences a considerable retardation in falling, from the action of the air. Where the arrival of the body at the bottom of the cavern to be measured cannot be seen, we must make allowance in our calculation for the known velocity of sound; thus, suppose a body were ascertained to fall in five seconds. As a heavy body near the earth’s surface falls about 16-1/12 feet in one second of time, or for this purpose 16 feet will be sufficiently exact; and as sound travels at the rate of 1142 feet per second, multiply together 1142, 16, and 5, which will give 91360, and to four times this product, or 365440, add the square of 1142, which is 1304164, and the sum will be 1669604; then if from the square root of the last number = 1292 the number 1142 be subtracted, the remainder 150 divided by 32 will give 4.69 for the number of seconds which elapsed during the fall of the body; if this remainder be subtracted from 5, the number of seconds during which the body was falling and the sound returning, we shall have 0.31 for the time which the sound alone employed before it reached the ear; and this number multiplied by 1142, will give for product 354 feet equal the depth of the well. This rule, which, it must be allowed, is rather complex, is founded on the property of falling bodies, which are accelerated in the ratio of the times, so that the spaces passed over increase in the square of the times.

The following is a more simple but less accurate rule. Multiply 1142 by 5, which gives 5710; then multiply also 16 by 5, which gives 80, to which add 1142, this gives 1222, by which sum divide the first product 5710, and the quotient 4.68 will be the time of descent, nearly the same as before. This taken from 5, leaves 0.32 for the time of the ascent; which, multiplied by 1142, gives 365 for the depth, differing but little from the former more exact number.

This superstition still prevails in many parts of England, especially in Cornwall, where the peasants on certain days of the year assemble at the springs, or holy wells, and, in the manner stated in the text, proceed to settle such doubts and enquiries as will not let the idle and anxious rest. Here, therefore, they come, and, instead of allaying, deservedly feed their uneasiness; the supposed responses serving equally to increase the gloom of the low-spirited, the suspicions of the jealous, and the passion of the enamoured. The superstition, however, is sanctioned by the highest antiquity. The Castalian fountain, and many others among the Grecians, were supposed to be of a prophetic nature. By dipping a fair mirror into a well, the Patræans of Greece received, as they supposed, some notice of ensuing sickness or health from the various figures portrayed upon the surface. In Laconia they cast into a pool, sacred to Juno, cakes of bread-corn; if they sank, good was portended; if they swam, something dreadful was to ensue. Sometimes they threw three stones into the water, and formed their conclusions from the several turns they made in sinking. “From the several waves and eddies which the sea, river, or other water exhibited,” says Dr. Borlase, “when put into agitation after a ritual manner, the ancients pretended to foretell with great certainty the event of battles; a way of divining recorded by Plutarch in his life of Cæsar, and still usual among the vulgar in Cornwall; who go to some noted well, at particular times of the year, and there observe the bubbles that rise, and the aptness of the water to be troubled, or to remain pure, on their throwing in pins or pebbles, and thence conjecture what shall or shall not befall them. The Druids also, as we have great reason to think, pretended to predict future events, not only from holy wells and running streams, but from the rain and snow water, which, when settled, and afterwards stirred, either by oak-leaf or branch, or magic wand, might exhibit appearances of great information to the quick-sighted Druid, or seem so to do to the credulous enquirer, when the priest was at full liberty to represent the appearances as he thought most for his purpose.”--Borlase’s Antiquities of Cornwall, p. 140.

In the islands of Scilly there is, or was some years since, a custom of propitiating fortune by certain ceremonies of this kind. An old islander regretted to a friend of the author the want of care with which such ceremonies had of late been conducted, and observed, as the consequence, that “they had no luck at all in the islands; not a wreck had taken place for many months.”

The Latin word moneta, for money, is probably more modern than pecunia, and is said to be derived from moneo, to advise or mark, that is, to show by some mark the weight and fineness of the metal of which coins were composed. Thus, according to Isidorus, “Moneta ita appellatur, quia monet nè qua fraus in pondere vel metallo fiat.” The origin of money seems to have been coeval with the first regulations of civil society, or, at least, it is too remote to be traced by any authentic history. Barter, that is the exchange of one commodity for another, was the ordinary mode of traffic in the earlier periods of the world; a practice which must soon have been discovered extremely inconvenient, and inadequate to the purposes of commerce; and hence the invention of a common measure, or standard, according to which all other things should be estimated. Writers very generally agree in believing that the metals were first used for such a purpose, as being almost the only substances whose goodness, and as it were integrity, were not injured by partition; and which admitted of being melted, and returned again into a mass of any size or weight. At first, it is probable that each person cut his metal into pieces of different sizes and forms, according to the quantity to be given for any merchandize, or according to the demand of the seller, or the quantity stipulated between them; to this end they went to market, laden with metal, in proportion to the purchase to be made, and furnished with instruments for apportioning it, and with scales for dealing it out, according as occasion required. By degrees it must have been found commodious to have pieces ready weighed; and Mr. Pinkerton observes, that such were prepared without any stated form or impression, but merely regulated to a certain weight; for weight was the grand standard of ancient coinage, so that all large sums were paid in weight, even down to the Saxon period of England. As in Greece the first estimation of money was merely by weight, so was it in Rome. Silver was the metal first used in Grecian coinage, but copper in the Roman; the former metal having been long known to the Romans. The first valuation of Roman money was by the libra gravis æris, or pound of heavy brass: and when by the progress of their conquests they obtained silver and gold, these were regulated in the same manner. Let us proceed one step farther in the history of coins; it is easy to imagine that the growing commerce of money being disturbed with frauds, both in the weight and the material, the interposition of public authority became necessary, and that hence arose the first stamps or impressions of money; to which succeeded the names of the moneyers, and at length the effigy of the prince, the date, legend, and other precautions to prevent the alteration of the species; and thus were coins completed. Gold and silver, in their pure or unmixed state, are too flexible to make coins sufficiently firm for general use; and hence the necessity of mixing with them a certain proportion of some harder metal, and this mixture is called the alloy. The quality of this alloy has been always considered of great importance with respect to the durability of coins. The most common metal used for this purpose is copper; and sometimes, for gold, a mixture of silver and copper. In all well-regulated governments, there has been a standard fixed by law; that is, a certain proportion between the quantity of pure metal and its alloy. In England the standard for gold is 11/12, that is eleven parts of pure metal, and one part of alloy. The standard for silver is 37/40, a proportion which is said to have been fixed in the reign of Richard I. by certain persons from the eastern parts of Germany, called Easterlings; and hence the word Sterling, which was afterwards the name given to the silver penny, and which is now applied to all lawful money of Great Britain.

Penny is derived by Camden from pecunia, but others suppose that the word is formed from pendo to weigh, and the word has been sometimes written, according to this origin, pending. The ancient English penny, or penig, or pening, was the first silver coin struck in England, and the only one current amongst our Saxon ancestors. Until the time of Edward I. the penny was struck with a cross so deeply indented in it that it might be easily broken, and parted into two pieces, thence called half-pennies, or into four, called four-things, or farthings; but that prince coined it without indenture; in lieu of which he first struck round half-pence and farthings.

By the term MEDAL, we understand a piece of metal, in the form of a coin, destined to preserve to posterity the portrait of some great man, or the memory of some illustrious action. They are distinguished by their different sizes; those of the larger size, or volume, are called medallions. Medallets is a name given by Pinkerton to those small pieces, or missilia, scattered among the people on solemn occasions; those struck for the slaves in the Saturnalia, private counters for gaming, tickets for baths and feasts, tokens in copper and lead, and the like. Medallions were certainly never intended to become current coin, as some medals probably were; they were struck purely to serve as public monuments, or to be presented by the emperor to his friends, and by the mint-makers to the emperor, as specimens of fine workmanship. They were struck upon the commencement of the reign of a new emperor, and other solemn occasions; and frequently, especially the Greek medallions, as monuments of gratitude, or of flattery. Sometimes they were trial or pattern pieces, testimonia probatæ monetæ; and such abound after the reign of Maximilian, with the “Tres monetæ” on the reverse. It is observed, that all the Roman pieces in gold, exceeding the denarius aureus; all in silver, superior to the denarius; and all in brass, superior to the sestertius, or what the medallist terms large brass, are comprehended under the description of medallions. Mr. Pinkerton, however, thinks that the gold medallions, weighing two, three, or four aurei only, passed in currency according to their size. Medallions from the time of Julius to that of Adrian, are very uncommon, and of very high price; from Adrian to the close of the western empire they are, generally speaking, less rare. The types of the Roman medallions are often repeated upon common coin; hence they appear of less importance than the Greek; impressions of which are frequently most uncommon, and nowhere else to be found. Many Roman medallions have S.C., as being struck by order of the senate; those without these initials, were struck by order of the emperor. Of Augustus, a noble medallion was found in Herculaneum. There are medallions of Augustus and Tiberius, struck in Spain; and one of Livia, at Patræ in Achaia. One in brass, of Antony and Cleopatra; reverse, two figures in a car, drawn by sea-horses. Of Tiberius there are many; and also of Claudius, Agrippina, Nero, Galba, Vespasian, and Domitian, &c. The Greek medallions of Roman emperors are far more numerous than the Roman; with a few exceptions, however, all medallions are rare and of princely purchase. Even in the richest cabinet, twenty or thirty specimens are esteemed a respectable proportion.

The parts of a medal are the two sides, one whereof is called the face, head, or obverse; the other the reverse. On each side is the area, or field; the rim, or border; and the exergum, which is beneath the ground, whereon the figures represented are placed. On the two sides are distinguished the type, and the inscription, or legend. The type, or device, is the figure represented; the legend is the writing, especially that around the medal; though in the Greek medals the inscription is frequently on the area. What we find in the exergum is, generally, no more than some initial letters, whose meaning we are usually unacquainted with; though, sometimes, they contain words that may be accounted an inscription.

The exergum sometimes contains the date of the coin, expressing in what consulship of the emperor it was struck, as Cos. III. upon the reverse of an Antoninus. Sometimes it signifies the place where it was struck, and to which the coin properly belonged, as S. M. AL. for Signata Moneta Alexandriœ, upon the reverse of a Licinius. Sometimes the name of a province, the reduction of which the medal is designed to celebrate; as Judæa on the reverse of a Vespasian. Medals usually have their figures in higher relief than coins.

We have stated that medals are of great importance to the study of history. They, indeed, furnish the principal proof of historic truth, as their evidence reaches to the most remote ages, as well as to the most remote countries. Vaillant, in his learned history of the Syrian kings, printed at Paris, 1681, first fixed the dates, and arranged the order of events in ancient historians, by means of these infallible vouchers. Thus he was enabled to ascertain the chronology and progress of events of three of the most important kingdoms of the ancient world; viz. those of Egypt, of Syria, and of Parthia. The study of the Roman medals has, in this respect, an advantage over that of Greek coins, since they serve not only to illustrate the chronology of reigns, but to aid us in the interpretation of particular events. To this purpose, besides the portrait of the prince, and date of his consulship, or of his tribunitian power, we have a representation, or poetical symbol, of some grand event on the reverse. In a word, the series of Roman coins presents the very best suite of documents relating to the Roman History. In addition to its historical importance, the medal is frequently a useful guide to geography, natural history, architecture, ancient monuments, busts, statues, ceremonies, and the like. See Addison’s Dialogues on the Usefulness of Ancient Medals. On this subject, also, Pinkerton, in his valuable work on medals, has some interesting remarks; he says that, to a man of poetical imagination, the Roman coins must prove an ample source of intellectual delight, by means of the fine personifications and symbols which are to be found on their reverse. Happiness has sometimes the caduceus, or wand of Mercury, which Cicero tells us was thought to procure the gratification of every wish. In a gold coin of Severus, she has heads of poppy to express that our prime bliss lies in oblivion of misfortune. Hope is represented as a sprightly damsel, walking quickly and looking straightforward. With her left hand she holds up her garments, that they may not hinder the rapidity of her pace; while, in her right hand, she holds forth the bud of a flower, an emblem infinitely more beautiful than the trite one of an anchor, which is the symbol of Patience, not of Hope. Abundance is imaged as a sedate matron, with a cornucopiæ in her hands, of which she scatters the fruits over the ground: but does not hold it up, and keep its contents to herself, as many poets and painters have represented her. Security stands leaning on a pillar, indicative of her being free from all designs and pursuits; and the posture itself corresponds to her name.

Coins also present us with countries and rivers admirably personified. On the reverse of a colonial coin, rude in execution, of Augustus and Agrippa, inscribed IMP. and DIVI. F., the conquest of Egypt is represented by the apposite metaphor of the crocodile, an animal almost peculiar to that country, and at that period esteemed altogether so, which is chained to a palm tree, at once a native of the country, and symbolic of victory. Moreover, a cabinet of medals, of which Rubens is said to have possessed a very magnificent one, may be considered as forming the classic erudition of a painter. We may add, that almost all the uses which connect the science of medals with painting, render it also subservient to the art of the sculptor, who cannot less than profit by the study of the Greek coins in particular. The connexion of the study of ancient coins with architecture, consists in the views of many of the ancient edifices, which are found in perfect preservation on medals. Froelich observes, that the coins of Tarsus are very remarkable for a kind of perspective in the figures. On others are found triumphal arches, temples, fountains, aqueducts, amphitheatres, circuses, palaces, columns, obelisks, baths, sea-ports, pharoses, and the like.

The study of medals affords such a variety of amusement and of instruction, that we may naturally suppose it to be nearly as ancient as medals themselves; and yet ancient writers do not furnish us with a single hint of collections of this kind. In the days of Greece, a collection of such coins as then existed would not be regarded as an acquisition of any great value, because it must have consisted only of those that were struck by the innumerable little states which then used the Greek characters and language, and of course it would be considered as a kind of domestic coinage, precluded from extension by the narrow limits of the intercourse that subsisted between different provinces and countries. As soon as any communication was opened between the Romans and the Greeks, the Grecian coins were imitated by the Roman workmen, and preserved in the cabinets of their senators among the choicest treasures. In a more advanced period of the Roman empire, individuals must have formed collections of Roman coins; for we find that a complete series of silver was lately found in our island, containing inclusively all the emperors down to Carausius. From the decline of the Roman empire, most branches of science were enveloped in darkness, till the revival of letters towards the end of the fifteenth century. When literature began to be cultivated in Italy, the study of medals, connected with that of ancient erudition, began to engage attention. Accordingly Petrarch, who in modern times was amongst the first persons in Europe that aspired to the celebrity of learning and genius, was likewise the first to revive the study of medals. This eminent man, having been desired by the Emperor Charles V. to compose a book that should contain a history of the coins of illustrious men, and to place him in the list, is said to have returned for answer, that he would comply with his desire, whenever the Emperor’s future life and actions deserved it. Availing himself of this circumstance, he sent that monarch a collection of gold and silver coins of celebrated men. “Behold!” said he, “to what men you have succeeded! Behold whom you should imitate and admire! to whose very form and image you should compose your talents! The invaluable present I should have given to no one but yourself; it was due to you alone. I can only know or describe the deeds of these great men: your supreme office enables you to imitate them.” In the next age, Alphonso, king of Arragon, caused all the ancient coins that could be discovered throughout the provinces of Italy to be collected, which he placed in an ivory cabinet, and always carried about with him, that he might be excited to great actions by the presence, as it were, of so many illustrious men in their images.

To those who are desirous of gaining information upon this interesting branch of antiquarian research, we strongly recommend Mr. Pinkerton’s Essay on Medals.

Having been led to offer these observations on ancient medals, we may, perhaps, be allowed to make one other digression on a subject naturally suggested by a visit to the vicarage of our reverend antiquary. The reader has been told, that “around his house he had arranged several precious relics, amongst which was an ancient cross, raised upon a platform on three steps.”

There is much obscurity with regard to the origin and uses of these stone crosses. We are, however, not disposed to enter into a discussion of such difficulty; but the reader may be gratified in having presented to him, in one view, a collection of such crosses as still exist in various parts of Cornwall.

Upon this subject, the reader is requested to turn to page 138, where it is stated that a body will permanently rotate only on its shortest axis. The philosophy of the fact is simply this--while a body revolves on its axis, the component particles of its mass move in circles, the centres of which are placed in the axis; a centrifugal force therefore is generated, which is resisted by the cohesion of the parts of the mass, and this tendency of each particle to fly off is expended in exciting a pressure upon the axis; and it is this strain which produces the effect in question, the axis of no pressure being alone the permanent axis.

Vis Inertiæ, p. 59.--The criticism of the vicar upon this subject is scientifically judicious; but the literary reader who has justly appreciated his character, may be inclined to ask how it could have happened that he should have overlooked the classical authority by which the expression is countenanced; we cannot answer the question, but we will supply the deficiency. The connecting two ideas, which at first sight appear opposed to each other, constituted a figure of speech much used both by the Greeks and Romans. Euripides delighted in it, which was a sufficient reason for Aristophanes to satirise it. Horace has given us several examples of it, as “Insaniens sapientia”--“Strenua inertia.”

Mechanical powers are simple arrangements by which we gain power at the expense of time; thus, if a certain weight can be raised to a certain height by unassisted strength, and the same thing is afterwards done with one tenth part of the exertion, through the use of a mechanic power, it will be found to occupy ten times as much time. In many cases, however, loss of time is not to be put in competition with the ability to do a thing; and since the advantages which the mechanical powers afford to man, by enabling him to perform feats which, without their assistance, would have been for ever beyond his reach, are incalculably great, the waste of time is overlooked, and is much more than balanced in the general result. It is true, that if there are several small weights, manageable by human strength, to be raised to a certain height, it may be full as convenient to elevate them one by one, as to take the advantage of the mechanical powers in raising them all at once; because the same time will be necessary in both cases: but suppose we should have an enormous block of stone, or a great tree, to raise; bodies of this description cannot be separated into parts proportionable to the human strength without immense labour, nor, perhaps, without rendering them unfit for those purposes to which they are to be applied; hence then the great importance of the mechanical powers, by the use of which a man is able to manage with ease a weight many times greater than himself.

To understand the principle of a mechanical power, we must revert to the doctrine of momentum. It will be remembered, that a small ball, weighing only two pounds, and moving at the rate of 500 feet in a second, will produce as much effect as a cannon ball of ten pounds in weight, provided it only moved at the rate of 100 feet in the same time; in like manner a ball weighing one pound may be made to balance another of five pounds, by placing it five times farther from the centre of motion; for in such a case, for every inch of space through which the large ball passes, the small one will traverse five inches, and will thus generate five times the momentum. This may be rendered still more evident by turning to page 161, and note thereon, where the see-saw is described, which, in fact, is a true mechanical power. It will be at once evident, from an inspection of the figure, that the lesser boy will pass over a much greater space, in equal time, than the greater boy, and thus generate more momentum, which compensates for his defect in weight, and renders him a balance for his heavier companion.--See note 23.

Those who have been in the habit of inspecting the works of the statuary, must frequently have detected the art which he has displayed in imparting stability to his figures, by lowering their centre of gravity. The bronze figure of Achilles, in Hyde Park, affords a very striking illustration of such ingenuity; it is evident, from the position and height of the figure, that, had not a mass of matter been added to its base, its stability would have been extremely precarious, since the slightest movement might have thrown its line of direction beyond the base; but the addition at the base renders such an accident impossible, by lowering its centre of gravity. Other examples of similar contrivance are presented in several celebrated statues, wherein stability is ensured by the judicious distribution of the draperies. In the celebrated statue of Peter at St. Petersburgh, the equilibrium of the mass is thus sustained by the introduction of a serpent twining upwards to his horse’s tail. The effect, however, is so unfortunate as to have given occasion for a wit to remark, “It is a very fine horse, but what a pity that he should have worms!” Nor have our celebrated painters overlooked a principle, the neglect of which would have withheld from the most symmetrical figures the charms of beautiful proportion.

“When a native of Macoushi goes in quest of feathered game, or other birds, he seldom carries his bow and arrows. It is the blow-pipe he then uses. This extraordinary tube of death is, perhaps, one of the greatest natural curiosities in Guiana. It is not found in the country of Macoushi. Those Indians tell you that it grows to the south-west of them, in the wilds which extend betwixt them and the Rio Negro. The reed must grow to an amazing length, as the part the Indians use is from ten to eleven feet long, and no tapering can be perceived in it, one end being as thick as the other. It is of a bright yellow colour, perfectly smooth both inside and out. It grows hollow; nor is there the least appearance of a knot or joint throughout the whole extent. The natives call it ourah. This, of itself, is too slender to answer the end of a blow-pipe; but there is a species of palma, larger and stronger, and common in Guiana, and this the Indians make use of as a case, in which they put the ourah. It is brown, susceptible of a fine polish, and appears as if it had joints five or six inches from each other. It is called samourah, and the pulp inside is easily extracted, by steeping it for a few days in water. Thus the ourah and samourah, one within the other, form the blow-pipe of Guiana. The end which is applied to the mouth is tied round with a small silk-grass cord, to prevent its splitting; and the other end, which is apt to strike against the ground, is secured by the seed of the acuero fruit, cut horizontally through the middle, with a hole made in the end, through which is put the extremity of the blow-pipe. It is fastened on with string on the outside, and the inside is filled up with wild bees-wax. The arrow is from nine to ten inches long. It is made out of the leaf of a species of palm-tree, called coucourite, hard and brittle, and pointed as sharp as a needle. About an inch of the pointed end is poisoned with the wourali. The other end is burnt, to make it still harder, and wild cotton is put round it for about an inch and a half. It requires considerable practice to put on this cotton well. It must just be large enough to fit the hollow of the tube, and taper off to nothing downwards. They tie it on with a thread of the silk-grass to prevent its slipping off the arrow.”

“The Indians have shown ingenuity in making a quiver to hold the arrows. It will contain from five to six hundred...

“...With a quiver of poisoned arrows slung over his shoulder, and with his blow-pipe in his hand, in the same position as a soldier carries his musket, see the Macoushi Indian advancing towards the forest in quest of powises, maroudis, waracabas, and other feathered game.

“These generally sit high up in the tall and tufted trees, but still are not out of the Indian’s reach; for this blow-pipe, at its greatest elevation, will send an arrow 300 feet. Silent as midnight he steals under them, and so cautiously does he tread the ground, that the fallen leaves rustle not beneath his feet. His ears are open to the least sound, while his eye, keen as that of the lynx, is employed in finding out the game in the thickest shade. Often he imitates their cry, and decoys them from tree to tree, till they are within range of his tube. Then, taking a poisoned arrow from his quiver, he puts it in the blow-pipe, and collects his breath for the fatal puff. About two feet from the end through which he blows, there are fastened two teeth of the acouri, and these serve him for a sight. Silent and swift the arrow flies, and seldom fails to pierce the object at which it is sent. Sometimes the wounded bird remains in the same tree where it was shot, and in three minutes falls down at the Indian’s feet. Should he take wing, his flight is of short duration; and the Indian, following the direction he has gone, is sure to find him dead. It is natural to imagine that, when a slight wound only is inflicted, the game will make its escape. Far otherwise; the wourali poison almost instantaneously mixes with blood or water, so that if you wet your finger, and dash it along the poisoned arrow in the quickest manner possible, you are sure to carry off some of the poison. Though three minutes generally elapse before the convulsions come on in the wounded bird, still a stupor evidently takes place sooner, and this stupor manifests itself by an apparent unwillingness in the bird to move.” ...

“The Indian, on his return home, carefully suspends his blow-pipe from the top of his spiral roof; seldom placing it in an oblique position, lest it should receive a cast.”--Waterton’s Wanderings in South America, p. 58.

A clock is nothing more than a piece of machinery to maintain the action of the pendulum, and at the same time to count and register the number of its oscillations; and by that peculiar property, that one vibration commences exactly where the last terminates, no part of time is lost or gained in the juxtaposition of the units so counted.

If some extraneous force were not applied, in a clock or watch, to maintain or perpetuate the natural vibrations of a pendulum, or oscillations of a balance, they would soon come to rest, by reason of friction in the mechanism, and the resistance opposed by the air to the parts in motion. This force, in the larger clocks, is usually a suspended weight; but, in the portable clock and watch, it is a spring coiled in a metallic box, that actuates the wheel-work by gradually unbending itself.

In the former of these cases, the weight is suspended by a cord or chain that is coiled round a cylinder when wound up, which cylinder being of uniform diameter throughout its length, is acted on by the cord, when fast at the interior end, by a similar force in every situation; and, therefore, imparts through the train, connected with its great wheel, invariable impulses to the escapement-wheel, at every vibration of the pendulum; which pendulum receives therefrom such a slight push, as is just sufficient to restore the momentum which it loses from friction and the air’s resistance, and thus the uniform motion of the pendulum is perpetuated. But when a spring is substituted for a weight, it is clear that its agency cannot be uniform, since, as the reader will learn by turning to page 101, it is a general law that elastic bodies, in the recovery of their form, after the removal of the compressing force, exert a greater power at first than at last, so that the whole progress of restoration is a retarded motion. It, therefore, became necessary to introduce some mechanical contrivance which might equalize such motion. This correction is effected by an apparatus termed a FUSEE, and is nothing more than the application of the wheel and axle; it is that conical barrel seen in most watches round which the chain coils in the act of winding up. When the fusee is full of chain, or the watch is wound up, the spring, through the medium of the chain, will act upon its upper part, which being very near the centre will give the spring but little power; but, as the spring uncoils and diminishes in strength, it will act upon a larger part of the fusee, until at last it gets to the bottom of it, and consequently, if the several increasing grooves upon it are made to increase in the same proportion as the power of the spring decreases, an equable force must be obtained.

Springs may be thus said to afford the means of packing up force, to be used whenever it is required. Mr. Babbage observes that the half minute which we daily devote to the winding up our watches is an exertion by which we pack a quantity of force, which is gradually expended during the ensuing twenty-four hours. Springs then will enable us to avail ourselves of inconstant and variable forces which must otherwise remain incapable of useful application, and the period may arrive when force will thus become an article of traffic, and machines be sent to the windmill to be wound up. The manner in which force is constantly allowed to run to waste is quite extraordinary in the present advanced state of science. We need only look at the working of the treadmill. The public are little aware of the enormous sums annually expended in towing vessels by steam from the Nore to the port of London; were floating treadmills established, the labour of those, upon whom punishment has been awarded, might be rendered available to the most important interests; whereas, with the present system, not only is this labour entirely lost, but is actually a source of expense, for machines, with all the accompaniments of engineers, are provided to counterbalance the force so uselessly generated.

The elastic property of iron springs has been lately exemplified in a very striking manner, by the invention of Pratt’s elastic chairs and beds; which, instead of the usual stuffing of feathers, are filled with iron wire!!! which is twisted into spiral form. Down itself cannot be more gentle or springy; it yields to pressure, and yet never becomes lumpy: beds thus constructed have the advantage of not heating the body; and, above all, they never require to be shaken or “made.” Had Vulcan fortunately made such a discovery before his ejectment from Olympus, his wife, Venus, would surely never have treated him with that contempt which mythologists have recorded of her; while her priestesses, the housemaids, must, in gratitude, have been bound to extend their protection to a benefactor, who could save them so much daily labour. For particulars of this curious invention, the reader may consult the Literary Gazette for March 17, 1827.

The phenomenon has been explained as depending upon the inertia of the parts of matter, which renders a certain time necessary in order to communicate to any body a sensible motion; so that when a body, moving with considerable velocity, meets with another of much greater size, it experiences almost as much resistance as if the latter were fixed. Nothing is easier to be divided than water; yet, if the palm of the hand be struck with some velocity against its surface, a considerable degree of resistance, and even of pain, is experienced from it, as if a solid body had been struck; nay, a musket ball, when fired against water, is repelled and even flattened by it. In like manner, if we load a musket with powder, and, instead of a ball, introduce a candle, and fire it against a board, the latter will be pierced by the candle end, as if by a ball. The cause of this phenomenon, no doubt, is, that the rapid motion with which the candle end is impelled, does not allow it time to be flattened, and therefore it acts as a hard body.

Impatiens, or Touch me not, affords a good example. The seed-vessel consists of one cell with five divisions; each of these, when the seed is ripe, on being touched, suddenly folds itself into a spiral form, leaps from the stalk, and disperses the seeds to a great distance by its elasticity. The capsule of the geranium and the beard of wild oats are twisted for a similar purpose. (Darwin’s Botanic Garden.) The seed-vessel of Euphorbia is extremely elastic, projecting the seeds with great force. An elastic pouch also serves to scatter the seeds of the Oxalis.

A very instructive toy might be constructed by placing a taper in the centre of a japanned waiter, to represent the sun, and fixing in a watch glass an indian rubber ball, with the parallels of latitude and meridians painted thereon, with the other characters of the globe. During its revolution around the candle, in consequence of the tendency of its centre of gravity to its lowest position, the diurnal and annual motions, and also the parallelism of its axis, will be represented, together with the concomitant phenomena.

If a cone, or sugar-loaf, be cut through in certain directions, we shall obtain figures which are termed conic sections; thus, if we cut through the sugar-loaf in a direction parallel to its base, or bottom, the outline or edge of the loaf where it is cut will be a circle. If the cut is made so as to slant, and not be parallel to the base of the loaf, the outline is an ellipse, provided the cut goes quite through the sides of the loaf all round; but if it goes slanting, and parallel to the line of the loaf’s side, the outline is a parabola, a conic section, or curve, to which this note more immediately relates. This curve is distinguished by characteristic properties, every point of it bearing a certain fixed relation to a certain point within it, as the circle does to its centre.

During the dreadful earthquake of Lisbon, bands of wretches took advantage of the general consternation to commit the most atrocious acts of robbery and murder. In fact, a considerable part of the city was destroyed by incendiaries, who, during the disaster, set fire to the houses, that they might pillage them with greater impunity.

Soils consist of a mixture of different finely divided earthy matter, with animal or vegetable substances in a state of decomposition. In order, therefore, to form a just idea of their nature, it is necessary to conceive different rocks decomposed, or ground into parts and powder of different degrees of fineness; some of their soluble parts dissolved by water, and that water adhering to the mass, and the whole mixed with larger or smaller quantities of the remains of vegetables and animals, in different stages of decay. Hence it will follow, that certain rocks will give origin to particular soils; thus poor and hungry soils, such as are produced from the decomposition of granite and sandstone, remain very often for ages with only a thin covering of vegetation; while soils from the decomposition of limestone, chalk, and basalt, are often clothed by nature with the perennial grasses; and afford, when ploughed up, a rich bed of vegetation for every species of cultivated plant. In adverting to this subject, Dr. Buckland, in his inaugural lecture, very justly observes, that it furnishes an instance of relation between the vegetable and mineral kingdoms, and of the adaptation of one to the other, which always implies design in the surest manner; for had not the surface of the earth been thus prepared for their reception, where would have been the use of all that admirable system of organization bestowed upon vegetables? And it is no small proof of design in the arrangement of the materials that compose the surface of our earth, that whereas the primitive and granitic rocks are least calculated to afford a fertile soil, they are for the most part made to constitute the mountain districts of the world, which, from their elevation and irregularities, would otherwise be but ill adapted for human habitation; whilst the lower and more temperate regions are usually composed of derivative or secondary strata, in which the compound nature of their ingredients qualifies them to be of the greatest utility to mankind by their subserviency to the purposes of luxuriant vegetation.

No doubt, then, can exist as to the important connexion between the geological structure of a country, and its degree of fertility; but the subject has not received the attention which it merits. And in the hope that this note may meet the eye of some zealous geologist, the author suggests the importance of commencing the enquiry in a primitive district; for, as we advance from a primitive to an alluvial district, the relations to which we have alluded become gradually less distinct and apparent, and are ultimately lost in the confused complication of the soil itself, and in that general obscurity which necessarily envelopes every object in a state of decomposition: we can, therefore, only hope to succeed in such an investigation, by a patient and laborious examination of a primitive country, after which we may be enabled to extend our enquiries with advantage through those districts which are more completely covered with soil, and obscured by luxuriant vegetation; as the eye, gazing upon a beautiful statue, traces the outline of the limbs, and the swelling contour of its form, through the flowing draperies which invest it.

The geological researches of Dr. Buckland have been long directed by a desire to accumulate facts to prove that there must have been an universal inundation of the earth; and, in his inaugural lecture, he has presented us with a summary of such facts, which, to use his own expression, whether considered collectively or separately, present such a conformity of proofs, tending to establish the universality of a recent inundation of the earth, as no difficulties or objections that have hitherto arisen are in any way sufficient to overrule.

In the year 1822, Dr. Buckland read a memoir before the Royal Society, announcing the discovery of a singular cave at Kirkdale in Yorkshire, containing an assemblage of fossil teeth and bones of the elephant, rhinoceros, hippopotamus, bear, tiger, and hyæna, and sixteen other animals; with a comparative view of five similar caverns in various parts of England, and others on the continent. For this important paper the society awarded to its author their Copley medal; and it constitutes the basis of a later and much more extended work, entitled “Reliquiæ Diluvianæ; or Observations on the Organic Remains contained in Caves, Fissures, and Diluvial Gravel; and on other Geological Phenomena, attesting the Action of an Universal Deluge. By the Rev. W. Buckland, B.D. F.R.S. &c.”

Let us explore the interior of this cavern. It was not till the summer of 1821, that the existence of any animal remains, or of the cavern containing them, was suspected. At this time, in continuing the operations of a large quarry, the workmen accidentally intersected the mouth of a long hole, closed externally with rubbish, and overgrown with grass and bushes. As this rubbish was removed before any competent person had examined it, it is not certain whether it was composed of diluvial gravel and rolled pebbles, or was simply the debris that had fallen from the softer portions of the strata that lay above it: the workman, however, who removed it, and some gentlemen who saw it, assured Dr. Buckland that it was composed of gravel and sand. In the interior of the cavern, our indefatigable geologist could not find a single rolled pebble, nor has he ever seen one bone, or fragment of bone, that bore the slightest mark of having been rolled by the action of water.

The original entrance is said to have been very small, and, having been filled up as above described, there could not have been any admission of external air through it to the interior of the cavern. Nearly 30 feet of its outer extremity have now been removed, and the present entrance is a hole in the perpendicular face of the quarry, about three feet high and five feet broad, which it is only possible for a man to enter on his hands and knees, and which expands and contracts itself irregularly from two to seven feet in breadth, and two to fourteen feet in height. It is unnecessary to enter into farther details; the reader, if he wishes more minute information, may consult Dr. Buckland’s work.

On entering the cave, the first thing observed was a sediment of soft mud or loam, covering entirely its whole bottom to the average depth of about a foot, and concealing the subjacent rock, or actual floor of the cavern. Not a particle of mud was found attached either to the sides or roof; nor was there a trace of it adhering to the sides or upper portions of the transverse fissures, or any thing to suggest the idea that it had entered through them. The mud was covered by a stalagmitic crust, which had been formed by the dripping of water impregnated with calcareous matter, as is common in all the cavities of limestone; but it is important to remark, that there was not any alternation of mud with any repeated beds of stalagmite, but simply a partial deposit of the latter on the floor beneath; so that the mud was encased, like meat in a pie, with an upper and under crust. It was chiefly in the lower part of the earthy sediment, and in the calcareous matter beneath it, that the animal remains were found.

In the whole extent of the cave, only a very few large bones have been discovered that are tolerably perfect; most of them are broken into small angular fragments and chips, the greater part of which lay separately in the mud, whilst others were wholly or partially invested with stalagmite, and others again mixed with masses of still smaller fragments. In some few places, where the mud was shallow, and the heaps of teeth and bones considerable, parts of the latter were elevated some inches above the surface of the mud and its calcareous crust; and the upper ends of the bones thus projecting, like the legs of pigeons through a pie crust, into the void space above, have become thinly covered with calcareous drippings, whilst their lower extremities have no such incrustation, and have simply adhering to them the mud in which they have been imbedded.

The effect of the loam and stalagmite in preserving the bones from decomposition, by protecting them from all access of atmospheric air, has been very remarkable.

The workmen, in first discovering the bones at Kirkdale, supposed them to have belonged to cattle that died by a murrain in this district a few years ago, and they were for some time neglected, and thrown on the roads with the common limestone; they were, at length, noticed by Mr. Harrison, a medical gentleman in the neighbourhood, and have since been collected and deposited in various private and public museums. The teeth and bones which have been discovered in this cave appear to have belonged to the hyæna, tiger, bear, wolf, fox, weasel, elephant, rhinoceros, hippopotamus, horse, ox, deer, hare, rabbit, water-rat, mouse, raven, pigeon, lark, snipe, and a small species of duck.

The bottom of the cave, on first removing the mud, was found to be strewed all over like a dog-kennel, from one end to the other, with hundreds of teeth and bones, or rather broken and splintered fragments of bones, of all the animals above enumerated; scarcely a single bone has escaped fracture, with the exception of some of the more solid and hard bones of the foot; on some of these bones marks may be traced, which, on applying one to the other, appear exactly to fit the form of the canine teeth of the hyæna that occur in the cave. The hyæna’s bones have been broken, and apparently gnawed equally with those of the other animals. Heaps of small splinters, and highly comminuted, yet angular fragments of bone, mixed with teeth of all the varieties of animals above enumerated, lay in the bottom of the den, occasionally adhering together by calcareous cement. Not one skull is to be found entire; and it is so rare to find a large bone of any kind that has not been more or less broken, that there is no hope of obtaining materials for the construction of a single limb, and still less of an entire skeleton. The jaw-bones, also, even of the hyænas, are broken to pieces like the rest.

It must already appear probable, from the facts above described, particularly from the comminuted and gnawed condition of the bones, that the cave at Kirkdale was, during a long succession of years, inhabited as a den by hyænas, and that they dragged into its recesses the other animals, whose remains are found indiscriminately mixed with their own: an hypothesis which is certainly strengthened by Dr. Buckland having found the excrement of the animal in the same cave. Should it be asked why we do not find, at least, the entire skeleton of the one or more hyænas that died last, and left no survivors to devour them; we find a sufficient reply to this question, in the circumstance of the probable destruction of the last individuals by the waters of the deluge. On the rise of these, had there been any hyænas in the den, they would have rushed out, and fled for safety to the hills; and if absent, they could not by any possibility have returned to it from the higher levels; that they were extirpated by the catastrophe is obvious, from the discovery of their bones in the diluvial gravel both of England and Germany.

The accumulation of these bones, then, appears to have been a process of years, whilst all the animals in question were natives of this country. The general dispersion of bones of the same animals through the diluvial gravel of high latitudes, over a great part of the northern hemisphere, shows that the period in which they inhabited these regions was that immediately preceding the formation of this gravel, and that they perished by the same waters which produced it. M. Cuvier has, moreover, ascertained that the fossil elephant, rhinoceros, hippopotamus, and hyæna, belong to species now unknown; and as there is no evidence that they have at any time, subsequent to the formation of the diluvium, existed in these regions, we may conclude that the period at which the bones of these extinct species were introduced into the cave at Kirkdale was before the deluge.

Thus the phenomena of this cave seem referable to a period immediately antecedent to the general deluge, and in which the world was inhabited by land animals, almost all bearing a generic, and many a specific resemblance to those which now exist; but so completely has the violence of that tremendous convulsion destroyed and remodelled the form of the antediluvian surface, that it is only in caverns that have been protected from its ravages, that we may hope to find undisturbed evidence of events in the period immediately preceding it. The bones already described, and the calcareous matter formed before the introduction of the diluvial mud, are what Dr. Buckland considers to be the products of the period in question. It was indeed probable, before the discovery of this cave, from the abundance in which the remains of similar species occur in superficial gravel beds, which cannot be referred to any other than a diluvial origin, that such animals were the antediluvian inhabitants not only of this country, but generally of all those northern latitudes in which their remains are found, (but the proof was imperfect, as it was possible they might have been drifted or floated hither by the waters from the warmer regions of the earth,) but the facts developed in this charnel-house of the antediluvian forests of Yorkshire demonstrate that there was a long succession of years, in which the elephant, rhinoceros, and hippopotamus had been the prey of the hyænas, which, like themselves, inhabited England in the period immediately preceding the formation of the diluvial gravel. Having thus far described the principal facts to be observed in the interior of this cave, Dr. Buckland proceeds to point out the chronological inferences that may be derived from the state of the bones, and of the mud and stalagmite that accompany them, and to extract the following detail of events that have been going on successively within this curious cave:--

First, There appears to have been a period (and, if we may form an estimate from the small quantity of stalagmite now found on the actual floor of the cave, a very short one,) during which this aperture in the rock existed in its present state, but was not tenanted by the hyænas.

The second period was that during which the cave was inhabited by the hyænas, and the stalactite and stalagmite were still forming.

The third period is that at which the mud was introduced and the animals extirpated, viz. the period of the deluge. It has been already stated, that there is not any alternation of this mud with beds of bone or of stalagmite, such as would have occurred had it been produced by land floods often repeated; once, and once only, it appears to have been introduced; and we may consider its vehicle to have been the turbid waters of the same inundation that produced universally the diluvial gravel.

The fourth period is that during which the stalagmite was deposited which invests the upper surface of the mud.

In concluding this note, we take the opportunity of recommending all those who feel interested in the researches of geology, to read a work lately published, entitled “The Wonders of Geology, by Gideon Mantell, LL.D. F.R.S. &c.”

Rifle guns are those whose barrels, instead of being smooth on the inside, like our common pieces, are formed with a number of spiral channels, resembling screws; except only that the threads, or rifles, are less deflected, making only one turn, or a little more, in the whole length of the piece. This construction is employed for correcting the irregularity in the flight of balls from smooth barrels, by imparting to the balls a rotatory motion perpendicular to the line of direction. The same effect has lately been accomplished by an extremely simple and obvious contrivance, and which will, probably, altogether supersede the necessity of rifling the barrel. It consists in cutting a spiral groove in the bullet itself, which, when discharged, is thus acted upon by the air, and the same rotatory motion imparted to it as that produced by the furrows in the barrel. But it is the rotatory motion which steadies the flight of the ball; and by whichever method this is produced, the theory of its action will be the same. It has been long and generally known, that when the common bullet is discharged from a plane barrel, its flight is extremely irregular and uncertain; it has, for instance, been found, from the experiments of Mr. Robins, that, notwithstanding the piece was firmly fixed, and fired with the same weight of powder, the ball was sometimes deflected to the right, sometimes to the left, sometimes above, and at others below the true line of direction. It has also been observed, that the degree of deflection increases in a much greater proportion than the distance of the object fired at. It is not difficult to account for these irregularities; they, doubtless, proceed from the impossibility of fitting a ball so accurately to any plane piece, but that it will rub more against one side of the barrel than another in its passage through it. Whatever side, therefore, of the muzzle, the ball is last in contact with, on quitting the piece, it will acquire a whirling motion towards that side, and will be found to bend the line of its flight in the same direction, whether it be upwards or downwards, to the right or left; or obliquely, partaking in some degree of both; and, after quitting the barrel, this deflection, though in the first instance but trifling and inconsiderable, is still farther increased by the resistance of the air; this being greatest on that side where the whirling motion conspires with the progressive one, and least on that side where it is opposed to it. Thus, if the ball, in its passage out, rubs against the left side of the barrel, it will whirl towards that side; and as the right side of the ball will, therefore, turn up against the air during its flight, the resistance of the air will become greatest on the right side, and the ball be forced away to the left, which was the direction it whirled in. It happens, moreover, from various accidental circumstances, that the axis of the ball’s rotation frequently changes its position several times during the flight; so that the ball, instead of bending its course uniformly in the same direction, often describes a track variously contorted. From this view of the causes of aberration in the flight of balls, it will be evident that the only means of correcting it is by preventing the ball from rubbing more against one side of the barrel than another in passing through it; and by giving to the bullet a motion which will counteract every accidental one, and preserve its direction, by making the resistance of the air upon the forepart continue the same during its whole flight; that is, by giving it a rotatory motion perpendicular to the line of direction. The contrivance for this purpose is called rifling, and consists, as we have before stated, in forming upon the inside of the barrel a number of threads and furrows, either in a straight or spiral direction, into which the ball is moulded; and hence, when the gun is fired, the indented zone of the bullet follows the sweep of the rifle, and thereby, besides its progressive motion, acquires a considerable one round the axis of the barrel, which motion will be continued to the bullet after its separation from the piece, so that it is constantly made to whirl round an axis coincident with the line of its flight. Many familiar examples of the utility and effect of rifling might be here adduced. If the bricklayer, while unroofing a house, be observed, he will be seen to give to the slates which he throws down a whirling motion, at a certain angle, which ensures their falling edgeways on the ground, and thus preserves them from fracture.

In relation to the subject in the text, to which this note refers, may be introduced a notice of the “Bommereng,” a missile used by the natives of Australia, and thus described by Major Mitchell in his “Journal of an expedition to the Rivers Darling and Murray.” “The bommereng, a thin, curved missile, about two feet four inches long, can be thrown by a skilful hand so as to rise upon the wind with a rotatory motion, and in a crooked direction towards any given point with great precision, and to return, after a considerable flight, to within a yard or two of the thrower; or, by striking the ground near him, to bound so as to hit at a great, distance, “en ricochet” any object behind a tree. This singular weapon probably originated in the utility of such a missile for the purpose of killing ducks, where they are very numerous, as on the interior rivers and lagoons, and where we accordingly find it much more in use than on the sea coast, and better made, being often covered with good carving.” This instrument may now be purchased in most of the London toy-shops.

If a stick be held at one of its extremities, and allowed to fall on the edge of a table, the farther end will rebound, or the hand will sustain a shock, unless it be struck exactly on the centre of percussion, in which case the stick will fall as a dead weight. The repetition of this simple experiment will readily convey to the young philosopher an idea of the nature of what is termed the centre of percussion.

It has been stated in the text, that the gyrations of the top depend exactly upon the same principle as that which produces the precession of the equinoxes; viz. an unequal attractive force exerted upon the revolving mass. In the one case, this is known to arise from the action of the sun and moon on the excess of matter about the equatorial regions of the earth; in the other, from the parts of the top being unequally affected by gravity, while it is spinning in an inclined or oblique position. To those philosophers who have condescended to read the present work, if there be any such, and are thereby induced to pursue the investigation of a subject which has hitherto excited far too little attention, we beg to submit the following remarks:--

If a top could be made to revolve on a point without friction, and in a vacuum, in the case of its velocity being infinite, it would continue to revolve for ever, in the same position, without gyration. If the velocity were finite, it would for ever remain unchanged in position, in the event of the centre of gravity being directly over the point of rotation. In any other position (supposing its velocity very great, although not infinite) there would arise a continued uniform gyration; the line which passes through the point of rotation, and the centre of gravity, always making the same angle with the horizon, or describing the same circle round the zenith. But in all artificial experiments the circumstances are very remarkably changed; if, indeed, the centre of gravity happens to be situated perpendicularly over the point of rotation, the top will continue quite steady, or sleeping, as it is termed, till nearly the whole of its velocity of rotation is expended. In any other position the top begins to gyrate, but reclining at all times on the outside of its physical point of gyration, the top is uniformly impelled inwards; and this (when the velocity is considerable, and the point broad) acts with a force sufficient for carrying the top towards its quiescent or sleeping point; but when the velocity is much diminished, this power becomes feeble, the gyrations increase in diameter, and the top ultimately falls.

The mechanical powers are all founded upon the principle that the lengths of circles are in proportion to their diameters; for it is an immediate consequence of this property of the circle, that if a rod of iron, or beam of wood, be placed on a point or pivot, so that it may move round its prop, the two ends will go through parts of circles, each proportioned to that arm of the beam to which it belongs; the two circles will be equal if the pivot is in the centre or middle point of the beam; but if it is nearer one end than the other, say five times, that end will pass through a circular space, or arc, five times shorter than the circular space the other end goes through in the same time. If, then, the end of the long beam goes through five times the space, it must move with five times the swiftness of the short end, since both move in the same time; and, therefore, any force applied to the long end must overcome the resistance of five times that force applied at the opposite end, since the two ends move in contrary directions; hence one pound placed at the long end would balance five placed at the short end.

The beam we have been describing constitutes the first of the mechanical powers, and is termed the LEVER. There are, besides, five others, viz. the wheel and axle; the inclined plane; the screw; the pulley; and the wedge; out of the whole, or a part of which, it will be found that every mechanical engine or piece of machinery is constructed.

The Lever being the simplest of all the mechanic powers, is in general considered the first. It is an inflexible rod or bar of any kind, so disposed as to turn on a pivot or prop, which is always called its fulcrum. It has the weight or resistance to be overcome attached to some one part of its length, and the power which is to overcome that resistance applied to another; and, since the power, resistance, and fulcrum admit of various positions with regard to each other, so is the lever divided into three kinds or modifications, distinguished as the first, second, and third kinds of lever. That portion of it which is contained between the fulcrum and the power, is called the acting part or arm of the lever; and that part which is between the fulcrum and resistance, its resisting part or arm.

In the lever of the first kind, the fulcrum is placed between the power and the resistance. A poker, in the act of stirring the fire, well illustrates this subject; the bar is the fulcrum, the hand the power, and the coals the resistance to be overcome. Another common application of this kind of lever is the crow-bar, or hand-spike, used for raising a large stone or weight. In all these cases power is gained in proportion as the distance from the fulcrum to the power, or part where the men apply their strength, is greater than the distance from the fulcrum to that end under the stone or weight. A moment’s reflection will show the rationale of this fact; for it is evident that if both the arms of the lever be equal, that is to say, if the fulcrum be midway between the power and weight, no advantage can be gained by it, because they pass over equal spaces in the same time; and, according to the fundamental principle already laid down, as advantage or power is gained, time must be lost; but, since no time is lost under such circumstances, there cannot be any power gained. If, now, we suppose the fulcrum to be so removed towards the weight, as to make the acting arm of the lever three times the length of the resisting arm, we shall obtain a lever which gains power in the proportion of three to one, that is, a single pound weight applied at the upper end will balance three pounds suspended at the other. A pair of scissors consists of two levers of this kind, united in one common fulcrum; thus the point at which the two levers are screwed together is the fulcrum; the handles to which the power of the fingers is applied, are the extremities of the acting part of the levers, and the cutting part of the scissors are the resisting parts of the levers; the longer, therefore, the handles, and the shorter the points of the scissors, the more easily you cut with them. A person who has any hard substance to cut, without any knowledge of the theory, diminishes as much as possible the length of the resisting arms, or cutting part of the scissors, by making use of that part of the instrument nearest the screw or rivet. Snuffers are levers of a similar description; so are most kind of pincers, the power of which consists in the resisting arm being very short in comparison with the acting one.

In the lever of the second kind, the resistance or weight is between the fulcrum and the power. Numberless instances of its application daily present themselves to our notice; amongst which may be enumerated the common cutting knife, used by last and patten makers, one end of which is fixed to the work-bench by a swivel-hook. Two men carrying a load between them, by one or more poles, as a sedan chair, or as brewers carrying a cask of beer, in which case either the back or front man may be considered as the fulcrum, and the other as the power. Every door which turns upon its hinges is a lever of this kind; the hinges may be considered as the fulcrum, or centre of motion; the whole door is the weight to be moved, and the power is applied to that side on which the handle is usually fixed. Nut-crackers, oars, rudders of ships, likewise fall under the same division. The boat is the weight to be moved, the water is the fulcrum, and the waterman at the oar is the power. The masts of ships are also levers of the second kind, for the bottom of the vessel is the fulcrum, the ship the weight, and the wind acting against the sail is the moving power. In this kind of lever the power or advantage is gained in proportion as the distance of the power is greater than the distance of the weight from the fulcrum; if, for instance, the weight hang at one inch from the fulcrum, and the power acts at five inches from it, the power gained is five to one; because, in such a case, the power passes over five times as great a space as the weight. It is thus evident why there is considerable difficulty in pushing open a heavy door, if the hand is applied to the part next the hinges, although it may be opened with the greatest ease in the usual method. In the third kind of lever, the fulcrum is again at one of the extremities, the weight or resistance at the other; and it is now the power which is applied between the fulcrum and resistance. As in this case the weight is farther from the centre of motion than the power, such a lever is never used, except in cases of absolute necessity, as in the case of lifting up a ladder perpendicularly, in order to place it against a wall. The man who raises it cannot place his hands on the upper part of the ladder; the power, therefore, is necessarily placed much nearer the fulcrum than the weight; for the hands are the power, the ground the fulcrum, and the upper part of the ladder the weight. The use of the common fire-tongs is another example, but the circumstance that principally gives this lever importance is, that the limbs of men and animals are actuated by it; for the bones are the levers, while the joints are the fulcra, and the muscles which give motion to the limbs, or produce the power, are inserted and act close to the joints, while the action is produced at the extremities; the consequence of such an arrangement is, that although the muscles must necessarily exert an enormous contractile force to produce great action at the extremities, yet a celerity of motion ensues which could not be equally well provided for in any other manner. We may adduce one example in illustration of this fact. In lifting a weight with the hand, the lower part of the arm becomes a lever of the third kind; the elbow is the fulcrum; the muscles of the fleshy part of the arm the power; and as these are nearer to the elbow than the hand, it is necessary that their power should exceed the weight to be raised. The disadvantage, however, with respect to power, is more than compensated by the convenience resulting from this structure of the arm; and it is no doubt that which is best adapted to enable it to perform its various functions. From these observations it must appear, that although this arrangement must be mentioned as a modification of the lever, it cannot, in strictness, be called a mechanical power; since its resisting arm is in all cases, except one, longer than the acting arm, and in that one case is equal to it, on which account it never can gain power, but in most instances must lose it.

The Wheel and Axle is the next mechanical power to be considered; it must be well known to every reader who has seen a village well; for it is by this power that the bucket is drawn up, although in such cases, instead of a wheel attached to the axle, there is generally only a crooked handle, which answers the purpose of winding the rope round the axle, and thus raising the bucket, as may be seen in the engraving at the head of our third chapter. It is evident, however, that this crooked handle is equivalent to a wheel; for the handle describes a circle as it revolves, while the straight piece which is united to the axle corresponds with the spoke of a wheel. This power may be resolved into a lever; in fact, what is it but a lever moving round an axle? and always retaining the effect gained during every part of the motion, by means of a rope wound round the butt end of the axle; the spoke of the wheel being the long arm of the lever, and the half diameter of the axle its short arm. The axle is not in itself a mechanical power, for it is as impotent as a lever whose fulcrum is in the centre; but add to it the wheel, and we have a power which will increase in proportion as the circumference of the wheel exceeds that of the axle. This arises from the velocity of the circumference being so much greater than that of the axle, as it is farther from the centre of motion; for the wheel describes a great circle in the same space of time that the axle describes a small one; therefore the power is increased in the same proportion as the circumference of the wheel is greater than that of the axle. Those who have ever drawn a bucket from a well by this machine, must have observed, that as the bucket ascended nearer the top the difficulty increased: such an effect must necessarily follow from the views we have just offered; for whenever the rope coils more than once the length of the axle, the difference between its circumference and that of the wheel is necessarily diminished. To the principle of the wheel and axle may be referred the capstan, windlass, and all those numerous kinds of cranes which are to be seen at the different wharfs on the banks of the river Thames. It is scarcely necessary to add that the force of the windmill depends upon a similar power. The treadmill furnishes another striking example. The wheel and axle is sometimes used to multiply motion, instead of to gain power, as in the multiplying wheel of the common jack, to which it is applied when the weight cannot conveniently have a long line of descent; a heavy weight is in this case made to act upon the axle, while the wheel, by its greatest circumference, winds up a much longer quantity of line than the simple descent of the weight could require, and thus the machine is made to go much longer without winding than it otherwise would do.

The Pulley is a power of very extensive application. Every one must have seen a pulley; it is a circular and flat piece of wood or metal, with a string which runs in a groove round it. Where, however, this is fixed, it cannot afford any power to raise a weight; for it is evident that, in order to raise it, the power must be greater than the weight, and that if the rope be pulled down one inch, the weight will only ascend the same space; consequently, there cannot be any mechanical advantage from the arrangement. This, however, is not the case where the pulley is not fixed. Suppose one end of the rope be fastened to a hook in the ceiling, and that to the moveable pulley on the rope a cask be attached, is it not evident that the hand applied to the other extremity of the rope will sustain it more easily than if it held the cask suspended to a cord without a pulley? Experience shows that this is the fact, and theory explains it by suggesting that the fixed hook sustains half the weight, and that the hand, therefore, has only the other half to sustain. The hook will also afford the same assistance in raising the weight as in sustaining it; if the hand has but one half the weight to sustain, it will also have only one half the weight to raise; but observe, says Mrs. Marcet, that in raising the weight, the velocity of the hand must be double that of the cask; for, in order to raise the weight one inch, the hand must draw each of the strings one inch; the whole string is therefore shortened two inches, while the weight is raised only one. Pulleys then act on the same principle as the lever, the deficiency of strength of the power being compensated by its superior velocity. It will follow, from these premises, that the greater the number of pulleys connected by a string, the more easily the weight is raised, as the difficulty is divided amongst the number of strings, or rather of parts into which the string is divided by the pulleys. Several pulleys, thus connected, form what is called a system, or tackle of pulleys. They may have been seen suspended from cranes, to raise goods into warehouses, and in ships to draw up the sails.

The Inclined Plane is a mechanic power which is seldom used in the construction of machinery, but applies more particularly to the moving or raising of loads upon slopes or hills, as in rolling a cask up or down a sloping plank into or out of a cart or cellar, or drawing a carriage up a sloping road or hill, all which operations are performed with less exertion than would be required if the same load were lifted perpendicularly. It is a power which cannot be resolved into that of the lever: it is a distinct principle, and those writers who have attempted to simplify the mechanical powers, have been obliged to acknowledge the inclined plane is elementary. The method of estimating the advantage gained by this mechanical power is very easy; for just as much as the length of the plane exceeds its perpendicular height, so much is the advantage gained; if, for instance, its length be three times greater than its height, a weight could be drawn to its summit with a third part of the strength required for lifting it up at the end; but, in accordance with the principle so frequently alluded to, such a power will be at the expense of time, for there will be three times more space to pass over. The reason why horses are eased by taking a zig-zag direction, in ascending or descending a steep hill, will appear from the preceding account of the action of the inclined plane, because in this way the effective length of the inclining surface is increased while its height remains the same.

The Wedge is rather a compound, than a distinct mechanical power; since it is composed of two inclined planes, and in action frequently performs the functions of a lever. It is sometimes employed in raising bodies; thus the largest ship may be raised to a small height by driving a wedge below it; but its more common application is that of dividing and cleaving bodies. As an elevator, it resembles exactly the inclined plane; for the action is obviously the very same, whether the wedge be pushed under the load, or the load be drawn under [sic] the wedge. But when the wedge is drawn forward, the percussive tremor excited destroys, for an instant, the adhesion or friction at its sides, and augments prodigiously the effect. From this principle chiefly is derived the power of the wedge in rending wood and other substances. It then acts besides as a lever, insinuating itself into the cleft as fast as the parts are opened by the vibrating concussion. To bring the action of the wedge, therefore, under a strict calculation, would be extremely difficult, if not impossible. Its effects are chiefly discovered by experience. All the various kinds of cutting tools, such as axes, knives, chisels, saws, planes, and files, are only different modifications of the wedge.

The Screw is a most efficient mechanic power, and is of great force and general application. It is in reality nothing more than an inclined plane formed round a cylinder, instead of being a continued straight line. Its power is, therefore, estimated by taking its circumference, and dividing this by the distance between any two of its threads; for what is taking the circumference of a screw, but another mode of measuring the length of the inclined plane which wraps round it? and taking the distance between one thread and the next to it, is but measuring the rise of that inclined plane in such length; and from the properties of the inclined plane, it follows, that the closer the threads of a screw are together in proportion to its diameter, the greater will be the power gained by it.

A cycloid is a peculiar curve line; and is described by any one point of a circle as it rolls along a plane, and turns round its centre; thus, for instance, the nail on the felly of a cart-wheel traces a cycloid in the air as the wheel proceeds. This curve is distinguished by some remarkable properties, the most important of which is that mentioned in the text, viz. that any body moving in such a curve, by its own weight, or swing, will pass through all distances of it in exactly the same time; and it is for such a reason that pendulums are made to swing in cycloids, in order that they may move in equal times, whether they go through a long or a short part of the same curve. Where the arc described is small, a portion of the circle will be sufficiently accurate, because it will be seen that such an arc will not deviate much from an equal portion of a cycloidal curve.

The cycloid is remarkable as being that path, with the exception of the perpendicular, through which a body will move with the greatest velocity; suppose, for example, a body is to descend from any one point to any other, by means of some force acting on it, together with its weight: a person unacquainted with mechanics would say at once, that a straight line is the path it must take to effect this in the shortest possible time, since that is the shortest of all lines that can be drawn between two points. Undoubtedly it is the shortest; notwithstanding which, however, the body would be longer in traversing it, than in moving through a cycloid. If a body were to move through a space of fifty or a hundred yards, by its weight and some other force acting together, the way it must take to do this in the shortest possible time is by moving in a cycloid. It is supposed that birds which build in the rocks possess an instinctive knowledge of this fact, and drop or fly down from height to height in this course. There is certainly a general resemblance between the curved path they describe on such occasions, and the cycloid, but it would be difficult to establish the fact by experiment. Man, however, has founded upon this principle some applications of great value in practical mechanics. In Switzerland, and in several parts of Germany, for example, slides have been constructed along the sides of mountains, by which the timber felled near their summits is conducted with extreme rapidity to the distant valleys.

This interesting game is of French origin (billiard, of bile, and from the Latin, pila, a ball). It was hailed as a favourite diversion at the court of Henry III. of France; and was thence communicated to all the courts of modern Europe. To the novice it may appear as a game of accidents and chances, but experience has enabled us to determine the effects of the stroke given to a ball with wonderful precision; and it is quite extraordinary to observe the accuracy with which an accomplished player can effect his object, by measuring with his eye the angle at which he should make the stroke, the position of the ball with respect to the cushion, and the distance of the point of the ball from its centre, at which it should be struck. By such skilful management the ball may be made to take directions which would, at first view, be regarded as contrary to all the known laws of motion, such, for instance, as passing round an object, such as a hat placed on the table, and to strike a ball behind it into a pocket.

Upon this subject the reader should consult a work by M. Mingaud, which has been translated and published by John Thurston, the celebrated billiard-table maker of Catherine Street, Strand. We understand that a still more complete work may be expected from the same source.

In investigating the effects produced upon bodies by collision, it is necessary to distinguish between elastic and non-elastic substances, since their motions after impact are governed by very different laws.

If two bodies, void of elasticity, move in one right line, either the same or contrary ways, so that one body may strike directly against another, let the sum of their motions before the stroke, if they move the same way, and the difference of their motions, if contrary ways, be divided into two such parts as are proportional to the quantities of matter in the bodies, and each of those parts will respectively exhibit the motion of each body after the stroke: for example, if the quantities of matter in the bodies be as two to one, and their motions before the stroke as five and four, then the sum of their motions is nine, and the difference is one; and therefore, when they move the same way, the motion of that body, which is as two, will, after the stroke, be six, and the motion of the other, three; but, if they move in contrary directions, the motion of the greater body after the stroke will be two-thirds of one, and of the lesser body one-third of one; for, since the bodies are void of elasticity, they will not separate after the stroke, but move together with one and the same velocity; and, consequently, their motions will be proportional to their quantities of matter; and it follows from the fact of action and reaction being equal, that no motion is either lost or gained by the stroke when the bodies move the same way; because, whatever motion one body imparts to the other, so much must it lose of its own; and, consequently, the sum of their motions before the stroke is neither increased nor diminished by the stroke, but is so divided between the bodies, as that they may move together with one common velocity; that is, it is divided between the bodies in proportion to their quantities of matter: but it is otherwise, where the bodies move in opposite directions, or contrary ways, for then the smaller motion will be destroyed by the stroke, as also an equal quantity of the greater motion, because action and reaction are equal; and the bodies, after the stroke, will move together equally swift, with the difference only of their motions before the stroke; consequently, that difference is, by means of the stroke, divided between them in proportion to their quantities of matter.