On the Inferences drawn by Drs. Magnus and Tyndall from their Experiments on the Radiant Properties of Vapour. By R. RUSSELL.

The author agreed in the main with Tyndall's deductions. He endeavoured to show that vapour of water had no power of transmitting its radiant heat into space. This proposition was supported by arguments from various natural phenomena.

On Parhelia, or Mock Suns, observed in Ireland.

By WILLIAM A. TRAILL, of the Geological Survey of Ireland.

The author began by stating that the above phenomena were analogous to the paraselence or mock moons, and though of not unfrequent occurence in northern latitudes, were in these countries of great rarity. The phenomena observed by him were seen on the 28th of January, 1869, near the village of Strangford (Co. Down), lat. 54° 21', long. 5° 35', west of Greenwich, and first appeared as three brilliant suns situated in the same horizontal line, about 15° to 20° above the horizon, and of equal brightness. The two outer, or mock suns, gradually assumed the prismatic colours, and lengthening out joined above, thus forming the "ordinary halo," in which the red colour was nearest to the real sun. Concentric and exterior to it was another prismatic halo, the "extraordinary halo," which was rather fainter, in which also the red colour was innermost.

Touching this latter externally was the "circumzenithal halo," which was by far the most brilliant of the three, lying as if horizontally overhead. In this likewise the red colour was next the sun, thus forming the outer periphery of the halo. The phenomena began a little after 2 P.M., and lasted only for about half an hour, attaining its greatest splendour at 2h 20m P.M.

Throughout the duration of the phenomena the sky was of a clear blue colour, and almost unobscured; a few light fleecy clouds were, however, drifting northward, slight "cirrus" clouds stretched across part of the sky, from E. to W., and throughout the whole time the points where the mock suns had first appeared continued the brightest.

With regard to the state of the weather at the time, the day was mild and fine, no rain falling till the evening. The sun was warm, but a cold southerly wind prevailed. The moon was full on the previous day, and exceptionally high springtides occurred along the N.E. portion of the Irish coast.

The barometer fell rapidly 7 inch within twelve hours. The wind veered round gradually through 140°, and increased in velocity from 6 to 38 miles an hour, the thermometer ranging from 42° to 46°, and towards evening the rain descended in torrents. The succeeding ten days or fortnight was characterized by excessively bad weather, rain, and storms.

The author lastly touched on the different theories by which these phenomena could be most easily accounted for.

THE PROGRESS OF SCIENCE.

Government Action on Scientific Questions.

By Lieut.-Col. A. STRANGE, F.R.S., F.R.A.S.

The author called attention to the number, variety, and importance of those national duties, involving Science, which can be performed by the Executive Government alone. He pointed out that the English Government possesses as yet no provision for regulating the performance of these duties in a systematic manner. He maintained that the requisite provision must consist of two additions to the existing administration, neither of which, however, unaccompanied by the other would suffice-namely, first, a Minister of Science; and, second, * From Observations at the Armagh Observatory.

a permanent Consultative Council, to advise the various departments through the Minister. His purpose was not to endeavour to uproot the existing system, but to graft upon it additions demanded by experience and the progress of knowledge. Assuming that the Minister would be appointed for his station, parliamentary ability, and political influence, he would need advisers, who should be a permanent, well-paid, and therefore a responsible Council of Science, representing all the main branches of science, the different arms of the military and naval services, commerce, agriculture, and the engineering profession. The Council should be quite independent of political influences. The author described the mode of election to the Council which he proposed, and in which he would give a certain voice to the Scientific Societies. The duties of the Council would befirst, to advise the Government on all questions arising in the ordinary routine of administration submitted to it by the various departments; second, to advise the Government on special questions, such as the founding of new scientific institutions and the modification or abolition of old ones, the sanctioning of scientific expeditions and applications for grants for scientific purposes; third, to consider and decide upon inventions tendered to Government for the use of the State; and, fourth, to conduct or superintend the experiments necessary to enable it to perform these duties. This would not entirely relieve the Government of all responsibility in scientific matters. The advantages to the nation accruing from a sound and comprehensive administration of science were incalculable.

The author referred, for fuller particulars regarding the subject, to his paper "On the Necessity for a Permanent Commission on State Scientific Questions," read before the Royal United Service Institution on the 15th of May last, and published in No. 64 of the Journal of the Institution.

Obstacles to Science-Teaching in Schools. By the Rev. W. TUCKWELL. After describing the slow progress made in scientific teaching since the Report of the Public Schools' Commission in 1864, and declaring that the first-class English schools teaching science systematically at the present momentcan be counted on the fingers of one hand, the author proceeded to show that the head masters were not altogether to be blamed for this state of things.

They have inherited an order of tuition some hundred years old, fortified with minute, unbroken venerable traditions, looked upon for ages past as the supreme instrument and test of intellectual power, whole and complete in itself, supported by immense experience, worked by tried machinery. Into the midst of this wellmapped, well-proved system is thrust a strange and foreign subject, comprising many branches, and demanding multifold appliances, whose value as a mental weapon they have had no means of testing; they are called upon to surrender to this a portion of the time which already seems too short for other work, and to inaugurate a department of school labour over which they can exercise no sort of supervision or control. They ask for guidance in the new arrangements which they are called upon to form; whether any one department is educationally fundamental to the rest; whether sciences of experiment should precede or follow those of observation; what portions of the old course are to be abandoned; how far the Universities, which in many cases stamp the practical value of their work, will recognize such abandonment. They look round for accredited teachers and approved text-books, for enlightenment as to the amount of apparatus and its cost, for details of teaching and of testing, and they look in vain. They must fall back upon their own moral consciousness, for no help is tendered to them from without. I place this helplessness of head masters first on the list of obstacles which we have to chronicle; and I plead, for the moment, in their behalf, almost more than in behalf of science. For their attitude is frank and cordial; they are prepared as a body to meet the demands of the scientific public loyally and with all their might. If those who are pressing modern subjects on them will entertain their just appeal and try to understand their difficulties, they will prove the best auxiliaries science can hope to gain; for they will bring to this new department of their work the same energy and wisdom, the same self-sacrificing impartial zeal, which have

already won for them the deserved esteem of the community; but if we fail to work in harmony with them, their want of sympathy and interest will be simply fatal to our schemes.

Next to this helplessness of head masters came the difficulty of obtaining properly trained and certificated science-teachers. With the admirable German system, comprising special examination of Candidates for Masterships, not only in knowledge, but in teaching power, together with a year of trial in some large school before entering on their work, was compared the insufficient test offered by the English University Degree, a high test, no doubt, of intelligence and knowledge, but not of power to communicate knowledge or to infuse intelligence. Third in rank amongst the obstacles to be surmounted was placed the cost of paying science masters; and the School Commissioners, now redistributing the endowments of the country, were urged to set apart funds for science-teaching in every large school, and to insist on their being faithfully expended for the purpose. The necessity of having good teachers was then dwelt on. The first condition of success in scientific, as of other teaching, is obviously the teacher. He must be a man thorough in his special knowledge, and, if his special knowledge is to be well balanced in reference to other subjects, of the widest general culture. He must not spend all his time in teaching, but must have leisure to prepare lessons and experiments. He must possess the delicate art of handling many pupils, the force of manner which attracts them, the enthusiasm which puts and keeps them en rapport with him, the insight which reads their minds, the tact which can preserve discipline without checking inquiry, and, possessing all this and more, he must be well and highly paid.

An exact estimate was offered of the cost of apparatus; and the value of workshops, museums, and other accessories of the kind was dwelt upon.

After glancing at the action of the universities, the author touched on a grave item in the catalogue of difficulties. Granting that scientific teaching is essential to a perfect education, the anxious question meets us-How is it to be inserted in the curriculum of an established school? We are told that, to meet the demands of University competition, the highest pressure is already put upon the time and brains of boys; and that if four hours a week are to be accepted as the minimum demand of science, classical work must suffer. And, in order to solve this problem, some well-known schools have instituted a system of bifurcation, to which the author was opposed. If linguistic training is bad without the rationalizing aid of scientific study, no less is exclusive science bad when divorced from the refining society of literature and philology; and an admission that certain institutions stunt particular faculties is oddly followed by a device which causes each to work unchecked. The difficulty must be met fairly, and on premises which scholars as well as savans can understand. It must be met by asking whether in purely classical schools no time is wasted; why it is that in the lower forms a boy takes years to master what a clever tutor teaches in a few months at home; why the weapon of analysis, which opens every other chamber of human knowledge, should be discarded in the case of scholarship alone; whether unattractiveness is an inherent vice in Greek and Latin only, or whether, if judicious method wakens pleasure and keeps alive attention, that of itself is not economy of time; whether, lastly, the day has not arrived when Greek and Latin verse-making may not be allowed to disappear. After having written some thousand Greek and Latin verses in his own school-days, the author pronounced them waste of time, and protested against them altogether. Their elimination from our school system will be clear gain in itself, and will set free at once a much larger amount of time than is demanded for the prosecution of natural science.

After enumerating at some length the details essential to the giving a fair place to science in education, the paper ended as follows:-"The summary of what I have to say is this, that our schools, in their readiness to establish science, must be aided from without. All questions of funds, of apparatus, of teachers, of selected text-books, of coordinated subjects, of University influence, and of united action come to the same point at last. We must have central leadership, at once commanding and intelligent, if the introduction of science into our schools is to be simultaneous and effective. The question has passed out of the realm of general

discussion; it is ripe, if ever a question was, for detailed and practical settlement. There must be within this Association, there must be within this room, men qualified in all respects to appreciate the nature of our difficulties, to formulate rules for our guidance, to press our pecuniary needs on those who are for a time the bursars of our educational endowments, to watch and influence the action of the Universities, as on other points, so especially in the projected 'Leaving Examinations. To them I confidently appeal. I appeal on behalf of countless schools, which, ready to admit reform, are helpless to initiate it. I appeal on behalf of those few schools which have initiated it, and are endeavouring courageously and honestly, but with little of useful concert, with much of wasted force, to work it out. Let it once be announced to the educational community that a committee of distinguished men, having at heart not merely scientific interests, but the interests of the Universities and the Schools, has been armed by this Association to counsel and to assist, to recommend and to accredit, to harmonize and to combine, to become, in short, the recognized representatives and controllers of scientific education, and they will not lack grateful clients, or attain inadequate results. If science is to flourish in the land, preliminary knowledge and training, bestowed with care upon our boyhood, must leave our manhood free for original research. If our English education is to be abreast of continental teaching, one half of our mental faculties must no longer be suffered to lie dormant. To have removed this great reproach, and to have helped this great reform, will be an achievement worthy to take high rank even amongst those splendid services to science and to the community which give lustre to the British Association."

CHEMISTRY.

Address by Professor ANDREWS, F.R.S. L. & E., President of the Section. AMIDST the vicissitudes to which scientific theories are liable, it was scarcely to be expected that the discarded theory of Phlogiston should be resuscitated in our day and connected with one of the most important generalizations of modern science. The phlogistic theory, elaborated nearly two hundred years ago by Beecher and Stahl, was not, it now appears, wholly founded in error; on the contrary, it was an imperfect anticipation of the great principle of energy, which plays so important a part in physical and chemical changes. The disciple of Phlogiston, ignorant of the whole history of chemical combination, connected, it is true, his phlogiston with one only of the combining bodies, instead of recognizing that it is eliminated by the minor of all. "There can be no doubt," says Dr. Crum Brown, who first suggested this view, "that potential energy is what the chemists of the 17th century meant when they spoke of phlogiston." "Phlogiston and latent heat," playfully remarks Volhard, which formerly opposed each other in so hot a combat, have entered into a peaceful compact; and, to banish all recollection of their former strife, have assumed in common the new name of energy." But, as Dr. Odling well remarks, "in interpreting the phlogistic writings by the light of modern doctrine, we are not to attribute to their authors the precise notion of energy which now prevails. It is only contended that the phlogistians had in their time possession of a real truth in nature, which, altogether lost sight of in the intermediate period, has since crystallized out in a definite form." But whatever may be the true value of the Stahlian views, there can be no doubt that the discoveries which have shed so bright a lustre round the name of Black mark an epoch in the history of science, and gave a mighty impulse to human progress. A recent attempt to ignore the labours of Black and his great contemporaries, and to attribute the foundation of modern chemistry to Lavoisier alone, has already been amply refuted in an able inaugural address delivered a short time ago from the Chair formerly occupied by Black. The statements of Dr. Crum Brown may, indeed, be confirmed on the authority of Lavoisier himself. Through the kindness of Dr. Black's representatives I have been permitted to

examine his correspondence, which has been carefully preserved, and I have been so fortunate as to find in it three original letters from Lavoisier to Dr. Black. They were written in 1789 and 1790, and they appear to comprise the whole of the correspondence on the part of Lavoisier which passed between those distinguished men. Some extracts from these letters were published soon after Dr. Black's death by his friends Dr. Adam Ferguson and Dr. Robison; but the letters themselves, as far as I know, have never appeared in an entire form. I will crave permission to have them printed as an appendix to this address. Lavoisier, it will be seen, addresses Black as one whom he was accustomed to regard as his master, and whose discoveries had produced important revolutions in science. It may, indeed, be said with truth that Lavoisier completed the foundation on which the grand structure of modern chemistry has since arisen; but Black, Priestley, Scheele, and Cavendish were before Lavoisier, and their claims to a share in the great work are not inferior to those of the illustrious French chemist.

d

Among the questions of general chemistry, few are more interesting, or have of late attracted more attention, than the relations which subsist between the chemical composition and refractive power of bodies for light. Newton, it will be remembered, pointed out the distinction between the refractive power of a medium and its refractive index, and gave for the former the expression, where the refractive index, and d the density of the refracting medium. Sir J. Herschel, anticipating later observations, remarked, in 1830, that Newton's function only expresses the intrinsic refractive power on the supposition of matter being infinitely divisible; but that if material bodies consist of a finite number of atoms, differing in weight for different substances, the intrinsic refractive power of the atoms of any given medium will be the product of the above function by the atomic weight. The same remark has since been made by Berthelot. Later observations have led to an important modification in the form of Newton's function. Beer showed that the experiments of Biot and Arago, as well as those of Dulong, on the refractive power of gases, agree quite as well with a simpler expression as with that given by Newton; and Gladstone and Dale proposed in 1863 the formula μ-1 as expressing more accurately than any other the results of their experiments on the refractive power of liquids. The researches of Landolt and Wüllner have fully confirmed the general accuracy of the new formula. An important observation made, about twenty years ago, by Delffs has been the starting-point for all subsequent investigations on this subject. Delffs remarked that the refractive indices of the compound ethers increase with the atomic weight, and that isomeric ethers have the same refractive indices. The later researches of Gladstone and of Landolt have, on the whole, confirmed these observations, and have shown that the specific refractive power depends chiefly on the atomic composition of the body, and is little influenced by the mode of grouping of the atoms. These inquiries have gone further, and have led to the discovery of the refraction-equivalents of the elements. By comparing the refractive power of compound bodies differing from one another by one or more atoms of the same element, Landolt succeeded in obtaining numbers which express the refraction-equivalents of carbon, hydrogen, and oxygen; and corresponding numbers have been obtained for other elements by Gladstone and Haagen. The whole subject has been recently discussed and enriched with many new observations in an able memoir by Gladstone. As might be expected in so novel and recondite a subject, some anomalies occur which are difficult to explain. Thus hydrogen appears in different classes of compounds with at least two refraction-equivalents, one three times as great as the other; and the refraction-equivalents of the aromatic compounds and their derivatives, as given by observation, are in general higher than the calculated numbers.

A happy modification of the ice-calorimeter has been made by Bunsen. The principle of the method (to use as a measure of heat the change of volume which ice undergoes in melting) had already occurred to Herschel, and, as it now appears, still earlier to Hermann; but their observations had been entirely overlooked by physicists, and had led to no practical result. Bunsen has, indeed, clearly pointed * Ordered by the General Committee to be printed among the Reports.