THE MONTH: SCIENCE AND ARTS.

The Report of the meeting of the British Association held last year at Glasgow has just been published in a goodly volume of more than three hundred pages. Among its contents are Reports of Committees, of which it may be said that the more widely they are known the better; and bearing in mind recent disasters at sea, the Investigation of the Steering Qualities of Ships by Professor Osborne Reynolds of Owens College, Manchester, appears the more interesting. 'The experiments of the Committee on large ships,' he remarks, 'have completely established the fact, that the reversing of the screw of a vessel with full way on, very much diminishes her steering power, and reverses what little it leaves; so that where a collision is imminent, to reverse the screw and use the rudder as if the ship would answer to it in the usual manner, is a certain way of bringing about the collision.' This is an important fact, for it is well known that collisions have been occasioned by the very means made use of to avoid them. And Professor Reynolds says further: 'It appears that a ship will turn faster, and for an angle of thirty degrees, in less room when driving full speed ahead, than with her engines reversed, even if the rudder is rightly used. Thus when an obstacle is too near to admit of stopping the ship, then the only chance is to keep the engines on full speed ahead, and so give the rudder an opportunity of doing its work. These general laws are of the greatest importance, but they apply in different degrees to different ships; and each commander should determine for himself how his ship will behave.... It is also highly important that the effect of the reversal of the screw should be generally recognised, particularly in the law courts; for in the present state of opinion on the subject, there can be no doubt that judgment would go against any commander who had steamed on ahead, knowing that by so doing he had the best chance of avoiding a collision.'

The statements thus set forth are illustrated by diagrams which shew the position of the vessel after reversal of the screw, and the position after steaming ahead. The latter shews that collision would be entirely avoided.

We frequently read that in future sea-fights the ram will be relied on for running down enemy's ships and sending them to the bottom. But where is the captain at the present day who has had experience of ramming, and of other evolutions which will be required in a fleet of steam ironclads under quite new conditions? Soldiers can go into temporary camps and get experience in 'autumn manœuvres;' but sailors cannot have mock-actions and run down ships which cost half a million sterling, nor venture to try the eighty-ton-gun on their consorts. Hence there will be very much to learn in the first great naval battle.

Under these circumstances, Professor Reynolds recommends that small steam-launches should be built of wood, each representing the exact form of one of our large ships, and that with these all possible manœuvres should be carried out, and officers make themselves familiar with all the effects of the screw on the rudder, with all the conditions of steering, with all the evolutions requisite to bring about or to avoid a collision, and with the effects of ramming. If strongly built of wood, these little vessels would withstand an experimental blow from the ram.

The value of such experiments would be real, for it is now known that the behaviour of a small copy of a ship is exactly the same as that of the great ship, in proportion to the size. The waves set up by the launch bear the same relation to her size as the waves of the ship do to the ship. The recognition of this law marks an epoch in the progress of naval architecture. Given a model, Mr Froude 'can now predict with certainty the comparative and actual resistance of ships before they are constructed.'

The Report of the Committee for investigating the circulation of the underground waters in the New Red Sandstone and Permian formations of England, and the quantity and character of the water supplied to various towns and districts from these formations, conveys information interesting to everybody—for everybody drinks. At Liverpool there are wells sunk in the New Red Sandstone which yield more than seven million gallons daily; at Birkenhead the same; at Coventry, Birmingham, and Leamington four millions and a half; at Nottingham nearly four millions; and at Warrington and Stockport more than a million and a half gallons every day. The total makes up a large quantity; but it is nothing in comparison with the supply which the whole area of the New Red may be expected to furnish. This area, says the Report, is certainly not less than ten thousand square miles in extent in England and Wales, with an average rainfall of thirty inches, of which certainly never less than ten inches per annum percolates the ground, which would give an absorption of water amounting to no less than one hundred and forty-three millions three hundred and thirty-six thousand gallons per square mile per annum; which, on an available area of ten thousand square miles, gives an annual absorption of nearly a billion and a half of gallons in England and Wales. As if to heighten the effect of this good news, we are told the 'New Red Sandstone Rock constitutes one of the most effective filtering media known.... It exerts a powerful oxidising influence on the dissolved organic matter, which percolates it to such an extent, that in the waters of certain deep wells, every trace of organic matters is converted into innocuous mineral compounds.' And again: 'Waters drawn from deep wells in the New Red Sandstone are almost invariably clear, sparkling, and palatable, and are among the best and most wholesome waters for domestic supply in Great Britain.' After reading this, may we not say that Undermere, about which no one will quarrel, is the lake whence great towns in the north should draw their water supply?

During the meeting of the British Association at Plymouth last August, the Mineralogical Society held their second annual gathering under the presidency of Mr Sorby, F.R.S., who in his address gave an account of a new method for determining the index of refraction of minerals, which can be readily employed in their identification. This seems a dry subject; but it is one likely to be valuable and interesting to mineralogists and chemists, and to lead to an entirely new branch of mineralogical study, and to the discovery of a new class of optical properties of crystals. For a proper understanding of the method, a knowledge of optics, of mathematics, and other branches of science would be necessary; but we may state generally that it is based on the fact, that if an object, when placed in focus for examination on the stage of a microscope, is covered with a plate of some highly refracting substance, the focal length is increased; in other words, the microscope must be raised a little farther from the object in order to restore the focus. The distance to which the microscope has been moved thus becomes a measure, which can be accurately determined on a scale to thousandths of an inch. By this measure, therefore, very minute differences of refraction can be determined, and the several minerals identified; and Mr Sorby, in conjunction with Professor Stokes, Sec. R.S., has arrived at certain definite conclusions, which, embodied in numerical tables, may ere long be consulted by all interested in the subject.

On this point Mr Sorby explained in his address: 'On applying this method to the study of various minerals, the difference is found to be very great. We can mostly at once see whether they give a single unifocal image or one or two bifocal images, and form a very good opinion respecting the intensity of the double refraction, and easily determine whether it is positive or negative.... These facts combined furnish data so characteristic of the individual minerals, that it would usually be difficult to find two approximately similar.... It has been said that in studying the microscopical structure of rocks it is often difficult to distinguish nepheline from apatite. But the index of nepheline is about 1.53, whereas that of apatite is 1.64, and such a considerable difference could easily be recognised in a section not less than one-fiftieth of an inch in thickness.'

The observations hitherto made prove that minerals may be ranged in classes according to their refracting power and their chemical composition. The fluorides are lowest in the scale, while quartz, corundum, the sulphides and arsenides, are among the highest. From these particulars it will be understood that researches into mineralogy have a prospect of becoming more and more interesting.

As we have a British Association for the Advancement of Science, so our neighbours across the Channel have a French Association. It met last August at Havre, and in a few of its fifteen sections manifested signs of activity. Among the meteorologists, diagrams were exhibited shewing clearly that the 'changes of pressure in the upper regions of the atmosphere are by no means similar to those at the surface of the earth; for when the pressure at the lower station decreases, it rises at the upper station, and the reverse; or when it is steady at the one, it rises or falls at the other.' A line of telegraph for meteorological purposes is now erected from Bagnères to the Pic du Midi, seventeen miles. The Pic is nine thousand feet high, and will be an interesting observing station, in constant communication with the lower regions. A proposition was made that the Transatlantic steam-ship companies should be requested to institute regular meteorological observations on board their vessels; and that the captive balloon of next year's Great Exhibition at Paris should be an observing station. Paris is chosen as the meeting-place of the Association for next year, and at the same time a free international meteorological congress will be held.

During recent years it has been said that the marshes and saltish depressions in the territory of Algiers and other parts of North Africa were once covered by the sea, and schemes have been announced for readmitting the sea by cutting channels from the Mediterranean. Mr Le Chatelier, a French chemist, says—the existence of the salts is not due to the drying up of a former sea, but to the masses of rock-salt which exist in the mountains. From these the salt is dissolved out by rain or by subterranean waters, and the saline solution percolates the soil to feed the artesian reservoirs which underlie the desert. These observations will require attention from geographers.

If any apology were required for a somewhat late notice of Dr Sayre's method of rectifying curvature of the spine, it would be found in the fact that among the arts the healing art holds an eminent place, and has special claims on every one's attention. Dr Sayre, an American, has this year visited England to make known his method of curing those malformations of the backbone under which many persons remain cripples for the whole of their life; and now that it is known, the wonder is that it was not thought of before. In carrying out the operation, the patient is lifted from the ground, and suspended by a support under the chin and back of the head: sometimes a support is placed under the armpits, and sometimes the arms are raised. In this position the weight of the pelvis acts on the crook in the spine, and pulls it straight; a bandage dipped in plaster of Paris is then bound round the body; a few iron splints are inserted in the bandage, and as the plaster dries, a mould is formed, which keeps the straightened bones in place. The suspension is now at an end; the patient is found to be an inch or two inches taller than before the operation, and can walk without limping. After a few days, the plaster-mould is cut up each side, to allow of removal for washing the body; but the two halves are quickly replaced and held in position by a bandage. In some instances six months' wearing of the plaster-mould effects a cure, and the patient enjoys an ease and activity never before experienced.

This method of cure contrasts favourably with the treatment which keeps the patient supine many weary months. As may be imagined, it succeeds better with children than with adults; but even adults have been cured. A case occurred at Cork, the patient being a woman aged twenty-two, and requiring a little mechanical pulling to assist in the straightening; but it was accomplished, and she walked out of the room two inches taller than she entered it.

Mr Hoppe-Seyler, a learned German, has published a paper on Differences of Chemical Structure and of Digestion among Animals, supported by numerous examples, which shew that according to the organism so is the power to form differences of tissue; and he sums up thus: 'Looking at the question broadly, we find that the chemical composition of the tissues and the chemical functions of the organs present undoubted relations to the stages of development, which shew themselves in the zoological system, as well as in the early stages of development of each individual higher organism. These relations deserve further notice and investigation, and are qualified in many respects to prevent and correct errors in the classification of animals. It is generally supposed that the study of development is a purely morphological science, but it also presents a large field for chemical research.' This concluding sentence is significant, and should have serious consideration.

Waste pyrites from the manufacture of sulphuric acid is, as regards hardness, a good material for roads when mixed with gravel; but chemically it is not good. In the neighbourhood of Nienburg, Hanover, where roads and paths were covered with waste pyrites, it was found that grass and corn ceased to grow; and a farmer on mixing well-water with warm milk, observed that the milk curdled. The explanation is, that the waste pyrites 'contained not only sulphide of iron and earthy constituents, but also sulphide of zinc, and that by the influence of the oxygen of the atmosphere and the presence of water, these sulphides were gradually converted into the corresponding sulphates;' and these, continually extracted by the rain-water, soaked into the soil, contaminated the wells, and produced other injurious effects.

The want of really efficient names to distinguish various kinds of manufactured iron has long been felt in the iron trade. The Philadelphia Exhibition gave rise to a Commission which, after discussion of the question, have recommended that all malleable compounds of iron similar to the substance called wrought-iron shall be called 'weld-iron;' that compounds similar to the product hitherto known as puddled steel, shall be called 'weld-steel;' that compounds which cannot be appreciably hardened when placed in water while red-hot shall be called 'ingot-iron;' and that compounds of this latter which from any cause are capable of being tempered, shall be called 'ingot-steel.'

By further exercise of his inventive abilities, Major Moncrieff has produced a hydro-pneumatic spring gun-carriage perfectly adapted for use in the field. A gun mounted on this carriage could be made ready for action within ten minutes after its arrival in the trenches.

The Science and Art Department have commenced the publication of a 'Universal Art Inventory, consisting of brief Notes of Fine and Ornamental Art executed before the year 1800 chiefly to be found in Europe.' This is a praiseworthy undertaking, for there are so many rarities of art which can never be seen by the multitude, which can never be moved from their place or purchased, that an inventory thereof with descriptive notes cannot fail to be of great utility. Nearly all the governments of Europe and many royal personages are co-operating in this work, which includes reproductions in possible instances. Some of these reproductions are well known to the frequenters of the South Kensington Museum; for example, the great mantel-piece from the Palais de Justice at Bruges; Trajan's Column from Rome; a Buddhist gateway from India, of the first century; a monument from Nuremberg, and other elaborate works. As a means of reference, this Inventory will be welcome to many a student, and as it necessarily will take many years to complete, there will be the pleasure of watching for fresh instalments of information. But all students should remember that 'the laws of design are as definite as those of language, with much the same questions as to order, relationship, construction or elegance; differing for dissimilar styles as for divers tongues. The pupil in design has similar obstacles to encounter with those of the schoolboy in his alphabet and grammar; the ability to use the pencil or the brush will no more produce an artist than the acquirement of the writing-master's art with Lindley Murray's rules will make a poet.'

Professor Justin Winsor, one of the American delegates to the conference of librarians held last month, points out with much earnestness that by the extension of libraries a great impetus may be given to national education, and an opening made at the same time for the employment of women. In America, pains have been taken to engage men and women in the work who are content to labour to attain the level of a far higher standard than the public at large have been usually willing to allow as the test of efficiency. 'We believe,' remarks the Professor, 'that libraries are in the highest sense public charities; that they are missionary enterprises; that it is to be supine if we are simply willing to let them do their unassisted work; that it is their business to see two books read instead of one, and good books instead of bad. To this end it has been urged that one of our principal universities shall have a course of bibliography and training in library economy.'

In reply to various correspondents, we beg to state that the information regarding the manufacture of vegetable isinglass in Rouen, which appeared under the head of A Few French Notes in No. 717 of this Journal, was taken from L'Armée Scientifique, a work compiled by the well-known French savant, M. L. Figuier. As there seems to be some difficulty in reconciling M. Figuier's statements with the present state of the process as carried on in France, we are making further inquiry, and hope to be able to give early and definite information.