taught in nearly all the academies and high schools in the land. Few cities report no teaching; and this circular is an attempt to catch the present aspect of affairs, and to assist and guide them. The supply of science students from the training colleges is increasing fast, and the number of teachers able to give labora. tory instruction will soon be equal to the demand. The teaching at some of the older colleges, where the accu tomed routine of a classical education cannot be dropped, is among the least satisfactory. The newer schools recognise science as a mental gymnastics and training equal to "Euclid's Elements and the Latin Grammar," always insi ting upon the importance of experiment with didactic instruction. In a great majority of cases, nevertheless, mere text-book work is done, and as such work is little else than mischievous cram, our report advises that it be left out in primary and intern ediate schools. Far better so, 'han a long series of lectures listened to term after term; for "three months of laboratory work will give more real insight into any science than a whole year's study of the printed page; the latter is like learning language from a grammar, only without attempting to translate or write exercises." It is specially urged, therefore, that the experimenting be done by the pupils, and the excellent results of such teaching, even to the youngest learners, are shown in very interesting cases quoted; and the same principle is followed in recommending that apparatus should be extemporised this also by the pupils especia ly. "It will be invaluable to the future teacher; it vastly increases his power to interest and instruct his pupils, and at the same time it deepens his own insight into the subjects taught" The value of physical and chemical knowledge to medical men, the inadequate training of many of whom in America we recently noticed, to naval officers, and to women, is specially indicated and enlarged upon. But any such appeal to practical motives is hardly necessary in America, for the complaint is also made that applied science is most in demand, while ure science and research are too commonly ignored.

AT the last meeting of the Anthropological Institute, held at 4, Grosvenor Gardens, the residence of the President, General Pitt-Rivers, F.R.S., who occupied the chair, Lord Talbot de Malahide read a paper on the Longevity of the Romans in North Africa. The author gave several instances of epitaphs and inscriptions on tombs of persons whose age had exceeded 100 years, in some cases an age of 120, 130, and even 140 years had been attained. An interesting discussion ensued in which Mr. Villiers Stuart, M.P., Mr. Moncure Conway, Capt. Cameron, Mr. John Evans, Mr. Francis Galton, Sir Joseph Fayrer, Dr. Allen Thomson, Mr. Carmichael, and the President took part. Capt. R. F. Burton read a paper on some Neolithic Stoi e Implements and other objects brought by himself and Capt. Cameron from Wásá, on the Gold Coast. A large number of objects were exhibited by the authors and Mr. Ross. General Pitt-Rivers read a paper on the Egyptian Boomerang, and exhibited several specimens. A large collection of L'ushman drawings was exhibited by Mr. M. Hutchinson.

A NEW Volume of the Classified Catalogue of the Library of the Royal Institution of Great Britain, by Mr. Vincent, the Librarian, is now ready; it includes the most important works published during the last twenty-five years, placed under their respective heads, accompanied by a Synopsis and Indexes of Authors and Subjects.

THE half yearly general meeting of the Scottish Meteorological Society will be held to day. The business consists of (1) Report from the Council of the Society; (2) Address by D. Milne Home, of Milne Graden, Chairman; (3) The Rainfall of the British Islands, by Alexander Buchan, Secretary; (4) The Climate of Jerusalem, by Alexander Buchan, Secretary.

IN a pa er recently read before the Asiatic Society of Japan, entitled "Religious and political ideas of the early Japanese;

beginnings of the Japanese nation, and credibility of the national records," Mr. B. H. Chamberlaln (according to the Japan Mail), after mentioning the difficulties which beset investigation, and giving an analysis of the religious and so-called historical traditions of early Japan, [roceeded to draw, both from the matter itself and from the manner in which it was put together in the hi to ies as we now have them, several conclusions as to the condition of the early Japanese, and the influences which moulded them into the united nation which meets us at the dawn of authentic history. The most important of the e conclusions were:-1. That there were three centres of legendary cycles in ar cient Japanese, Idzumo, Yamato, and Kinshsiu, and that the country was probably divided into three or even a greater number of states. 2. That instead of having only begun to communicate with the mainland of Asia at about the year 200 A.D., as was commonly supposed, there had never been, so far as we can judge, a time when communication did not exist, and that much of the so-called autochtoncus civilisation was really imported, as was proved by a sifting of myths, and even by the test of language, the most archaic form of Japanese, containing a number of Chinese words for implements or ideas that had themselves been borrowed. 3. That authentic history did not in Japan go back farther than A. D. 400, i.e. more than a thousand years later than the date commonly accepted for its commencement. Mr. Chamberlain noticed in detail the items scattered through Kozhiki, or oldest monument of Japanese literature, relative to the governmental arrangements and religious belief of ancient times, and showed that Shito was not a religious system Į roperly so-called, but rather a Lundle of miscellaneous and often inconsistent superstitions.

DURING a heavy thunder: torm in the Shetland Islands on Tue day, which lasted several hours, a hill, three miles from Lerwick, was struck by lightning, and huge masses of rock and débris were thrown down on the public road which the hill overhangs, filling up the road and the valley at the other side, and uspending traffic. The total weight of the fallen rock is estimated at 4c0 tons.

LAST week the statue of Mariette Bey, the great French Egyptologist, was unveiled at Boulogne, in presence of a large assembly, including several high officials of the French Re, ublic.

THE report on the proposed grant to the French Minister of Po ts and Telegraphs of a sum of 3600., in view of the meeting of Electricians, has been sent to the French Senate, after having been adopted by the Chamber of Deputies. This meeting will take place only in October. One of the reasons alleged for the delay is the necessity of installing the magnetic instruments now in course of con: truction for the Observatory of Paris. The assent of the Fre ch Senate is stated to be beyond a doubt.

FROM the "Mineral Statistics of Victoria" for 1881 we see that the quantity of gold raised last year was 858,850 oz., being 29,729 oz. more than the quantity obtained in 1880. deepest shaft in the Colony is the Magdala at Stawell, which is 2409 feet deep.

The

SOME instructive results have been recently obtained by M. Spring, in studying the dilatation of isomorphous substances (Bull. Belg. Acad., No. 4). He experimented with five alums. These, he hows, expand very regularly, and very little with rise of temperature from zero till a critical temperature is reached (different for each), at which there is rapid expansion, indicating decomposition. Up to 60°, the mean critical temperature, these alums may be said to expand equally, and M. Spring is led to affirm that isomorphous substances have the same coefficient of expansion, or at least coefficients very little different. A probable inference is that they have the same coefficient of com pressibility; this he has yet to test. Thus, a similarity in

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Log. distance from Earth. 0'2614

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14 12 21 56 The calculated intensity of light on August 9 is equivalent to that at the first Harvard College observation on March 19.

COMET-SEEKING IN THE SOUTHERN HEMISPHERE.-From a communication to the Sydney Morning Herald, we learn that Mr. Tebbutt, of Windsor, N.S.W., the discoverer of the great comet of 1861, has, at the instance of the Boston (U.S.) Scientific Society, undertaken the organisation of a corps of amateur comet-seekers in Australia, and with this object has addressed a circular to several persons in the colonies, who have manifested an interest in the science. We wish Mr. Tebbutt every success: the matter could not be in better hands. It would be easy to adduce numerous cases where the theories of these bodies have suffered from the want of southern observations, and it may be hoped, that in conjunction with the systematic search undertaken by a number of observers in America, and, we are glad to add, in this country also, it will be quite an exceptional case for a comet within range of ordinary telescopes to escape detection, as we know many have done in past years. The additions to the number of comets of short period during the last fifteen years, are alone a sufficient inducement to institute more systematic examination of the heavens in future.

PHYSICAL NOTES

AN organ-pipe sonometer is described in the American Journal of Science, by Mr. Le Conte Stevens. The ordinary resonance box of the sonometer is in this instance replaced by a double organ-pipe of spruce fir-wood, tuned to give the note C=132 vibrations. Three steel wires are stretched above, two being tuned to the fundamental, the other strained to various degrees of tension by a lever and a sliding weight. There are also arrangements for sharpening or flattening the note of one of the pipes at will, so as to produce beats. By varying the windpressure, the natural harmonics of the pipes can be produced. The object of the instrument is to afford a convenient means of producing the notes of the natural scale and those of the tempered scale, by way of contrasting them with one another. The apparatus has several other uses as a lecture instrument in acoustics.

M. CAILLETET has invented a new pump for compressing gases to a high degree of compression. The main point in its construction is the method by which he obviates the existence of useless space between the end of the piston-plunger and the valve, which closes the end of the cylinder. This he accomplishes by inverting the cylinder and covering the end of the plunger with a considerable quantity of mercury. This liquid piston can of course adapt itself to all the inequalities of form of the interior space, and sweeps up every portion of the gas, and presses it up a conical passage into the valve. The valve by which the air enters the body of the pump is opened by a cam. gearing after the descent of the piston below point where the

air rushes in.

ANOTHER Suggestion due to M. Cailletet is worthy of notice, and is applicable to many pieces of laboratory apparatus beside air-pumps. It is the employment of vaseline as a lubricant wherever there is a liability of the presence of mercury; for, as is known, most oils and fatty matters clog with finely-divided mercury, and are objectionable on this account.

NEW forms of secondary battery continue to make their appearance, most of them based upon the accumulator of Planté.

Mr. R. E. Crompton has lately patented a process, for giving a large effective surface to the leaden electrodes by making it porous, by adding to the lead some other substance capable of being extracted by the action of acid, or by heat, or by other reagents. Another modification due to Messrs. Biggs and Beaumont, consists in collecting in a separate vessel the hydrogen or other products of decomposition, in the accumulator, the collected products being afterwards recombined as fast as required. The electrodes in this case are composed of finely divided lead.

WE have also received a report of a lecture delivered by M. Maurice Lévy before the Societé d'Encouragement on the same subject of electrical units. It speaks volumes for the mathematical education given in the public schools of Paris, if an audience of a society comparable to that of our Society of Arts could follow the lecturer through a mathematical discussion like that before us, which includes a discussion of the doctrine of dimensional equations, and of the elimination of arbitrary coefficients. M. Lévy applauds the decisions of the Congress, which he expounds logically and elegantly.

current.

THE following experiment of Messrs. Jamin and Maneuvrier illustrates the presence of an inverse electromotive force in the voltaic arc, dependent on the actions therein excited by the A continuous current was passed first from coke to mercury, producing a reddish coloured arc. The current was then reversed, when the arc appeared green, and the metal volatilised rapidly. Then the current of an alternating Gramme machine was passed through the same arrangement. The are now appeared green, showing a predominance of the current from mercury to coke, although in ordinary circumstances the two alternately directed currents are absolutely equal in strength.

THE decisions of the Electrical Congress have ar used the electricians of several Continental nations to realise the advance in exact science which the adoption of a uniform system of electrical units implies; and not to be behindhand, they are striving to spread a knowledge of what has been done. The new determination which is to be made of the value of the ohm has furnished material for several discussions, in which it is curious to observe the suggestions that were brought forward as new. Others content themselves with expounding that which has been already done. We have before us, from the pen of Dr. Guglielmo Mengarini, assistant in the Physical Institute of the University of Rome, a "History of the Electromagnetic Unit of Resistance," reprinted from the official bulletin of the Minister of Public Instruction. Beginning with the work of Davy, Becquerel, Oh, and Wheatstone, the author describes how gradually the rheostat brought forth the resistance-coil, and the units of Siemens and of the British Association. He then gives a theoretical discussion of the absolute electromagnetic unit of resistance, and an account of the methods of Weber and of the British Association for determining it. The main points in the propositions submitted to the International Congress at Paris in 1881 are then given, together with the formal decisions of the Congress thereupon.

A VALUABLE contribution to the subject of the electricity of flame has been lately made by Herren Elster and Geitel (Wied. Ann. No. 6). The discrepancies in previous results are attributed largely to the behaviour of the air layer immediately outside of the flame having been left out of account. The authors used a Thomson quadrant electrometer for measurement. They find the supposed longitudinal polarisation of flame merely apparent, and due to unequal insertion of the wires used as electrodes. On the other hand, flame is strongly polarised in cross section; an electrode in the air about the flame is always positive to one in the flame. The theory the authors adopt is this:-By the process of combustion per se free electricity is not produced in the flame; but the flame-gases and the air-envelope have the property of exciting, like an electrolyte, metals or liquids in contact with them. To this electrolytic excitation is added a thermo-electric, due to the incandescent state of the electrodes. The amount and nature of the electric excitation is independent of the size of the flame, and dependent on the nature, surface-condition, and glow of the electrodes, and on the nature of the burning gases. Inter alia, it is remarked that flames may be combined in series like galvanic elements, and so as to form a "flame-battery."

IN a recent dissertation (Wied. Ann. No. 7), Herr Heine describes experiments on the absorption of heat by gas-mixtures with varying percentage of constituents, and he thence deduces a method of ascertaining the amount of carbonic acid in the air. Varied mixtures of CO, and air, in known proportions, were

formed in a tube to which the heat of a Bunsen burner was admitted (through a rock-salt plate); and the resultant variations of pre sure were recorded by means of a Knoll pantograph. The curve obtained (with percentages as abscissæ and indicated pressures recorded as ordinates) shows, as one might expect, a decrease of rise of pressure through absorption of heat, with decrease of CO, but the two are not proportional. With regular decrease of CO, from 100 per cent., the fall is slight, in the curve, to about 5 per cent., and thereafter rapid to zero with pure air. (Mixtures of CO, and I gave a different curve, with a much lower position throughout.) By chemical methods the CO, has been shown to vary between o'02 and 0'05 per cent. Hence it was desirable to develop the corresponding part of the curve just described with special care. This was done, and atmospheric air, freed from moisture, but not from CO2, was admitted to the apparatus. The tabulated results of fifty analyses made thus, in four days, at Giessen, appear to prove the applicability of the method. (The proportion of CO, varied between 0'020 and 0°034.) Its advantages are: only small quantities of air (one or two litres) being required, and the operations being quite simple, and taking little time (say half an hour). It is suggested that the aqueous vapour in air may be similarly

measured.

A THIRD instalment of researches on transpiration of vapours, by Herr Steudel, at the instance of Prof. Lothar Meyer, is described in Wied. Ann. No. 7; it relates to alcohols and their halogen derivatives, and to some substitution-products of ethane and methane. In a concluding paper Prof. Meyer reviews the inquiry. The supposition is confirmed, that homologous series, even with very different molecular weight, have for the most part nearly the same constants of friction. (All compounds containing one carbon atom show strong divergence.) The influence of the nature of the contained atoms, on friction, is remarkable. Thus, with about equal molecular weight, iodine produces a much greater friction than bromine, and the latter a greater than chlorine. Far-reaching conclusions as to the form of molecules, Prof. Meyer is not prepared to draw, but the cross section of the molecule of a tertiary butylic compound is inferred to be less than that of the corresponding secondary, and the latter less than that of the primary. This agrees with received views as to the linking of these compounds. The molecular volumes reckoned from the friction of vapours, stand to each other in nearly the same ratios as the molecular volumes in the liquid state at boiling point.

FROM observations made several years ago, Prof. von Reusch of Tübingen was led to think the hydrophane of Czernowitza a substance peculiarly well fitted for diffusion experiments with gases. Its properties in this relation have now been carefully studied by Herr Hufner (Wied. Ann. No. 6); and inter alia, it is shown that the resistance to passage of a number of gases is related both to the coefficients of absorption and the specific gravities; all three increasing in the same sense (but not in simple proportion).

AN interesting analogy to thermoelectric phenomena, &c., is given by M. Bouty in the Journal de Physique (June). Suppose a tubular ring, impermeable to heat, containing in its lower half sand saturated with water, and in its upper air saturated with water-vapour. If heat be applied at one end (A) of the sand, a circulation is set up, the water being vaporised at A, condensed at the opposite end B, and filtering through the sand to replace the water evaporated at A. Again, suppose (instead of heat) a rotary pump acting about the middle of the air space; a circulation is produced, and the water evaporating at A causes a fall of temperature, while the condensation at B causes a rise; an image is thus presented of Peltier's phenomenon. The junction A, which is cooled, is precisely the one which must be heated to produce the existing circulation, and the quantity of heat absorbed at A is proportional to the weight of water evaporated per second, that is, to the intensity of the current.

SIGNOR MARTINI (N. Cim. [3] 9, 1881) obtains diffusion figures thus: A glass vessel is filled with two liquids little differing in density, e.g. water and an aqueous solution of salt or sugar. They are left at rest for an hour. A capillary tube entering the bottom of the vessel is connected by caoutchouc tubing with a movable vessel of coloured alcohol. When the latter enters by the capillary, it rises as a thin spiral thread, but on reaching the lighter liquid it spreads into fine tree-shaped figures. Figures of umbrella shape are produced, if the heavier liquid be used in place of the alcohol.

PROF. T. C. MENDENHALL, of Columbus, Ohio, communicates to the American Journal of Science a paper on the Influence of Time on the Change of Resistance of the Carbon Disk of Edi on's Tasimeter. This resistance was found, when pressure was removed suddenly, to return to its maximum value; but when pressure was applied, time was necessary to enable the resistance to reach its minimum. On applying pressure, the resistance fell a little more than 3 per cent. in one minute, about 5 per cent. in three minutes, and about 10 per cent. in one and a half hours.

CONTRARY to the opinion now generally received concerning the alleged change of resistance of carbon under pressure, Mr. Mendenhall, in the communication alluded to in the preceding note, asserts that the effect is not due to better surface contact. pressed lampblack buttons resting in its place in the tasimeter, His own experiments were made with one of Edison's comand covered by an "upper contact piece." This is all the information given upon this vital point of how the contacts were made, and in the absence of any evidence of care or precautions to ascertain whether the contact was perfect or not, the opinion pronounced must be regarded as worth very little.

GEOGRAPHICAL NOTES

THE Journal of the Straits Branch of the Bengal Asiatic Society for December, 1881, contains a short comparative vocabulary of the Fijian and Maori (New Zealand) languages, with notes by Mr. Thurston and Sir F. A. Wild. The Maori is a recognised member of the Eastern Polynesian linguistic family, and from these specimens the Fijian might be supposed to belong to the same connection. But the natives, especially of the eastern islands of the Fiji Archipelago, have long been exposed to Polynesian influences, through their relations with the Tonga i-landers. These influences are apparent both in their physical type and in the numerous dialects current on the coast. But the skulls of the Kai Colos occupying the interior of Viti Levu have been shown by Prof. Flower to be of a distinctly Papuan character. In fact, they are the most dolichocephalic on the globe. The outward appearance of the Kai Colos and other tribes removed from contact with the Tonga people also closely resembles that of the pure Melanesians of the New Hebrides and Solomon groups. Specimens of their speech have not yet been collected; but it may be taken for granted that it will be found to be of a distinctly Melanesian type, betraying little or no affinity to the Polynesian. Such vocabularies as these, while possessing a certain value, are apt to be very misleading, and have in fact contributed to the current belief that the Polynesian and Melanesian tongues are fundamentally one. In reality they possess nothing in common beyond the verbal resemblances due to the wide-spread Polynesian influences in the Melanesian domain. In their morphology and inner structure, the two systems are radically distinct.

HIRT, of Breslau, has published a second part of the "Geographische Bildertafeln," by Dr. Oppel and Heir Arnold Ludwig, the first part of which we noticed recently. This part is devoted to typical landscapes, and the selection seems to us to have been made with great discrimination. For Great Britain, for example, we have Loch Ness in Scotland, a Scotch Moor, the Giants' Causeway, the Dover Coast, a Welsh Valley, and an extensive landscape on the Upper Thames. All the other leading countries of Europe are treated after a similar fashion, while representative scenes are given from the great divisions of the other continents. The interest and utility of such a collection are obvious. The same publisher issues also a coloured panorama, showing the chief forms of the land and water on the surface of the globe, much superior to the publications of the same class with which we are familiar in this country.

LIEUT. GIRAUD has sailed from Marseilles for Zanzibar, as leader of a French expedition which proposes to take up African exploration where Livingstone laid it down with his life on the south shore of Lake Bangweolo. Lieut. Giraud proposes to go either direct west to Lake Tanganyika, or, more probably, by the north shore of Lake Nyassa, to the Chambeze River. This he will follow to its outlet in Lake Bangweolo, which he proposes to circumnavigate. He will then attempt, in canoes, to sail down the Luababa-Congo, to its mouth in the Atlantic Ocean. This is an ambitious programme; and every one interested in African exploration will wish the expedition complete success.

THE current number of the British Quarterly Review contains an article on recent Japane e progress, which is by far the most valuable that has been published on this ubject for many years past. The author, Col. H. S. Palmer, R.E., describes fully the cau es and course of the changes which have passed over the "Land of the Rising Sun" in the past fourteen years; the vari us and complicated changes in the constitution and administration-from the pure oligarchy which succeeded the revolution of 1868, to the system of tolerably free local government of the present day-are clearly expla ned, and the effect of the various steps in these changes made comprehensible to the general reader. The writer then takes the recent reforms u: der various heads-the army, navy, education, public works, prisons, &c.and shows, by statistics, what advance has really been made. The last half of the paper is, in fact, a comprehensive summary, with running commentary, of the Japanese government statistics in every department. The knoty subject of finance is treated with as much clearness as the subject admits of. Under this head the almost inevitable character of the present financial depression is explained; but it is gratifying to notice that a careful and impartial observer like Col. Palmer is able to conclude his article with confidence in the future of the country to which he has devoted so much study. Many of the in' ere: ting stati tics in the paper have already appeared in the columns of NATURE.

DR. HOLUB has sent us several papers connected with his South African explorations. There are two on the English in South Africa, from the standpoint of exploration and civilisation, and a similar paper on the French in Tuis; and an interesting Catalogue, with notes, of Dr. Holub's ethnographical collections.

IN connection with Egyptian troubles, Mr. Wyld has published two maps, which may be useful to those who are wa'ching operations. One is a plan of Alexandria and the harbour, with an inset map showing the British possessions in the Old World; the other is a small map of the Isthmus of Suez and Lower Egypt, on the scale of twelve miles to an inch, with a similar inset map.

CONTRIBUTION OF ASTRONOMY TO THE PROBLEM OF MOLECULAR PHYSICS1 THE kind way in which you have received me, leads me to fix, by writing, the principal points of our conversation on Sunday last. I thank you heartily for offered help to realise the scientific aim I have in view, and which I will now explain.

The synthetic study of thermo-chemical phenomena, of the laws of thermo-dynamics and of experiments relating to these subjects of the physical sciences, has brought us to consider the temperature of a body as being the mean amplitude of the vibratory oscillation of molecules constituting that body.

This definition, tal en as a starting point, enables us to explain and deduce all the essential laws of the mechanical theory of heat. We obtain from it easily the law of Dulong and Petit, that of isomorphism in systems of crystallisation, the relations connecting the coefficients of expansion of all substances with their atomic weight, their temperature of fusion and their density, &c.

The maximum tensions are calculated in advance with all exactness, and lastly, the two great mechanical principles of heat are an immed ate and necessary consequence of it.

I have, then, every reason to believe that this definition will be adopted, since it satisfies as well the condition of integrability of the differential equation of notion (function S of Zeuner) as the definition drawn from the air or mercury thermometer (definition of Regnault).

In that case, what is the specific heat of a body?

The specific heat becomes the sole manifestation of the attraction of molecules for one another.

Indeed, if we n ultiply the space traversed (temperature) by the molecular force (specific heat), we obtain the total heat or quantity of absolute work which the substance contains.

Here, consequently, comes in an important question, which is by no means secondary, as has often been said—

Is the attraction of matter for matter a fundamental essential property of matter, or is it merely the result of the dynamical action of the medium in which the matter exists?

In other terms, may one say, without its being possible to exA letter from M. Raoul Pictet to M. Dumas, dated Paris, December 16, 1881, and published in Archives des Sciences, June 15.

plain it, Matter attracts matter without the active intermediary of the medium; or, Attraction as a force does not exist; it is merely the manifestation of shocks of the ether which tend to approxi• mate bodies according to the Newtonian law?

In the former case, one regards the attractive potential of matter as an original capital placed in each material element, a capital which is only exhausted by the absolute approximation of all matter existing in the universe. In the latter case this potential is nil, and one supposes that a certain quantity of Finetic energy has been communicated in the beginning of time to the mass of the universe, a quantity of energy which is inevitably transformed under a thousand different combinations into all the physico-chemical and astronomical phenomena of nature.

In the former case § m2 + the potential is constant.

In the latter, mv2 alone is constant. The solution of this important question is necessary to establish physical theories in a somewhat distinct manner, and to prove the intimate relation existing between the various elements of bodies.

On the hypothesis that attraction is an essential property of matter, we shall liken it to inertia; tbus any body will possess as primordial characters, a certain quantity of inertia, without which we should never come to be put in contact with it nor to know it, and a certain quantity of attraction, which will be the manife-tation of its proper influence on the rest of the univer: e. Such will be the conditions of existence of matter.

On the hypotheses that m v2 alone is constant, inertia and motion are the fundamental properties of matter; shocks are the means of transformation of different modes of motion. Let us take, then, any body and heat it.

If we are partisans of the first hypothesis, that of potential, we must expect to find simple relations between the inertia of the body considered, the attraction of the molecule for one another, and increase of volume of the body, the whole a sociated with the quantity of mechanical work furnished to the body in the form of heat.

The specific heats and latent heats will then be functions of the atomic weight or inertia of the body, and the dissociation which is manifested by fusion and volatilisation, will be deduced from the study of the body under these two aspects, masses et in motion, and potential of those masses.

If we are partisans of the second hypothesis, supposing that mis constant, we are obliged simply to consider the volume of the body; that is to say, the exterior: urface of the smallest quantity of matter.

Indeed, shocks alone explain the phenomena. But when one says shock, he says surface where the shock occurs. The greater the surface the larger the number of shocks of the ether, the stronger the reaction of the matter.

We must expect them, in this second hypothesis, to find simple relations between the volumes of atoms and of molecules, that is, between the co-efficients which represent the den ity of the bodies, the number of atoms and the atomic weight, and the specific heats, latent heats, and maximum tensions.

In other terms, in the first hypothesis, molecular physics will rest essentially on the atomic weight, which, by virtue of the fall of bodies, represents simultaneously the idea of inertia and that of attraction, essential properties; in the second hypothe is the physico-chemical phenomena are deduced mainly from the volume of atoms and the medium in which the phenomena

Cccur.

The medium becoming active, a variation of medium wil induce in phenomena of attraction concomitant variations quite independent of matter itself.

The specific heats and the latent heats may then be variable elements in the same substance and at the same temperature under the same pressure, according to the mechanical energy of the medium in which the phenomena occur.

Thus the whole of molecular physics is closely connected with the solution of this theoretical question.

We have sought an experimental method capable of throwing some light on this problem. Without entering into too minute details, we will explain the plan of this work.

It may be accepted, I believe, that the solar system is nearly independent, mechanically speaking, of the rest of the universe; that is to say that no motion, relatively to the centre of gravity of this system, is produced in cur planets by the perturbation of other systems surrounding us.

We may then call M the total mass of the solar sy tem. This mass is decomp sed into m, m3, m2. . . the respective masses of the Sun, Venus, the Earth, Jupiter, &c., and the mass of