SCIENCE IN ITALY*

THE energetic revival of scientific activity in Italy, to which

attention has been before directed, still progressing satisfactorily. The mere fact that the Transactions of the Royal Institution of Lombardy report the proceedings of the sittings of the 24th June, of the 4th and 18th of July, of the "ordinary sittings of the 1st August," and "the solemn sittings of the 7th of the same month," afford to any Englishman who has summered on the Plains of Lombardy, very strong presumptive evidence of scientific enthusiasm and industry. Even in our lukewarm climate such meetings are suspended during the summer months, in spite of the insatiable activity of Englishmen. It does not appear that the worship of the "dolce far niente" has profaned the Milanese shrine of science.

In the course of these summer meetings thirty-nine original papers, besides academical reports and addresses, were read. During the year ending August 7, ninety such papers were read in the Department of the Mathematical and Natural Sciences, including subjects in pure and applied mathematics, hydraulic engineering, physical geography, astronomy, experimental physics, chemistry, natural history, animal and vegetable physiology, geology, agriculture, anthropology, anatomy, pathology, surgery, therapeutics, hygiene, medical statistics, and the history of science. In addition to these a number of original papers were read in the Department of Literature and Moral and Political Science. This statement of the quantity of work done is a sufficient exeuse for my not attempting anything like a complete analysis of it. A few of the most interesting papers may however be mentioned.

June, 20.-"On the Anthropometry of 400 criminals in the Penitentiary of Padua." This is an analysis and a summary of the results obtained by Dr. Pellizzari and Dr. Berretta, the full record of which fills a large volume. Some curious results come out of the tables of these measurements. The tallest and heaviest men are those who have committed murder and manslaughter; the shortest and lightest those who have committed rape. The head measurements are very interesting and suggestive, sufficiently so to warrant a continuation of such investigations over an area sufficiently large to obtain more reliable averages than the 400 measurements afford. There is another paper of the same date by Dr. Giglioli, that I suspect will prove very interesting to comparative anatomists, on remarkable teeth of whales (Cetodonti) that collected by Sig. Corelli, among other things, during a residence of forty years at Rio de Janeiro.

some

were

July 4.-"On the epoch of the upheaval of the sienitic rocks of the chain of Adamello, in the Province of Brescia."-" On another analogy between electrical and magnetic polarity," by Prof. Cantoni. (Another paper in continuation on the same subject was read on July 18.)-Note on the "Heat of Combination of Bodies," by Prof. Cantoni. This contains some suggestive speculations on the philosophy of thermodynamics, in which the author points out experimental difficulties, and goes a long way in the direction of atom-splitting, in order to find an explanation. He compares the combination of two chemical atoms or molecules, to a collision between two stellar systems or nebule, where the development of heat would not be merely that due to the velocity of each system considered as a whole, but in addition to this, to the disturbance of rotatory and orbital motion of the planets, satellites, &c., within each system. He supposes the ordinary atom or molecule to be a system of minor atoms, having orbital and rotatory movements, the disturbance of which, when atomic collision occurs, contributes to produce the heat of combination, It is not for me, a heretical disbeliever in the existence of either atoms or molecules, to make any comment on the merits of such a hypothesis.

"On the Drainage of the Lago Fucino" by Carlo Possenti, refers to an important undertaking which is proceeding at the cost and risk of Prince Torlonia. The author points out the difficulties and possible sources of failure of the enterprise.

"On the Prediction of the Movement of Tempests and the Phenomena which accompany them," by M. Harold Tarry, Vice-Secretary of the Meteorological Society of France; communicated by Prof. Schiaparelli. This is an exceedingly interesting paper, mainly based upon observations made by the author on the great cyclones which have deposited in Italy some of the sand uplifted from the desert of Sahara, &c. It is worthy of a special and separate abstract.

"Rendiconti del Reale Istituto Lombardo," for July, August, and September, 1872.

July 18.-"On the Velocity of Molecular Movements in Aeriform Fluids," by Prof. Brusotti. This is a contribution to the mathematical theory of thermodynamics.

"On the Origin of Atmospheric Electricity," a series of experiments on the electrical disturbances due to the rarification and condensation of air, both in its ordinary condition and when subjected to artificial dessication with a view to answer the ques tion proposed.

"On the Burning of Dead Bodies," by Dr. G. Polli. The author points out many sanitary, economical, and sentimental objections to the existing customs of burying the dead, and advo cates a revival of the ancient system of rapid decomposition by burning and preservation of the ashes, in order to satisfy sanitary requirements of the public, and the affections of friends and relatives.

Prof. Corradi contributed a long and interesting account of the voluminous manuscripts of Lazzaro Spallanzani, obtained in 1801 by the communal library of Reggio from Dr. Nicolo Spallanzani, the brother of Lazzaro. A perusal of this paper shows that the industry and attainments of this great naturalist were more extensive than we are accustomed to suppose in England. His manuscripts in Italian, French, and Latin are collected in 193 volumes, and include travelling diaries, notes of experiments and observations, letters, &c., some of which have been already published.

Besides these I may refer to Prof. Stoppani's observations on the eruption of Vesuvius April 24, 1872, and also to Prof. G. Cantoni's researches on the Rust of Wheat; but cannot attempt any account of their contents without extending this notice much beyond its proper limits.

The "solemn sitting" of the August 7 was chiefly devoted to the annual addresses of the Secretaries of the Mathematical and Physical, and of the Literature and Moral and Political De. partments, Sig. Luigi Cremona, and Sig. Guilio Carcano, and to other annual business.

I should add that a monthly meteorological report is regularly published, with the Transactions of this society.

The papers in the Department of Literature and Moral and Political Science are few in number. Passing over the mere literature altogether, I may refer to one paper on a strictly scientific subject which in Italy, as in England, is too commonly left in the hands of mere talkers and writers, who discuss many things and investigate very few or none. Í allude to political economy, and to a paper by Prof. Marescotti on Rent and Profit. This paper abounds in political argument, rather than political science. The author describes the rent of land as the remuneration of the landed proprietor for the capital although writing for the purpose of justifying the payment which he has invested in rendering the soil productive, and of rent, appears quite unacquainted with Ricardo's demonstration of the natural and independent origin of rent, as another element totally distinct from the reimbursement of the proprietors' outlay on the land.

Italiana, and the Transactions of the Academy of Sciences of the
Institute of Bologna must be reserved for another notice.
W. MATTIEU WILLIAMS

The summer and autumn numbers of the Gazetta Chemica

SCIENTIFIC SERIALS

THE Geological Magazine for the present month (No. 103) opens with a note by the editor on fossil remains of insects which have been described in previous volumes of the magazine, as an introduction to a paper by Mr. A. G. Butler describing a most interesting wing of a butterfly belonging to the Nymphalide group, found in the Stonesfield slate. This butterfly Mr. Butler proposes to name Paleontina oolitica, and, as he remarks, it is the most ancient member of its group yet discovered.-Mr. R. H. Tiddeman describes the Victoria Cave at Settle in Yorkshire, and notices the fossils contained in the lowest deposit yet reached in the investigation of this cave.-Mr. W. Molyneux notices the occurrence of copper and lead ores in the Bunter conglomerate of Carnock Chase; and Prof. King, of Galway, communicates a paper on the microscopic characters of a silo-carbacid rock from Ceylon, and notices their bearing on the methylotic origin of the Laurentian limestones, methylotic being a term introduced by the author to express the character of rocks which have undergone change by the elimination

of or additions to the substances of which they were originally composed. This paper, of course, bears indirectly on the vexed question of the nature of Eozoon.

The

Poggendorf's Annalen der Physik und Chemie, No. 11. first paper in this number is by A. Wüllner, being a continuation from vol. cxliv. of his researches "On the Spectra of the Gases in Geissler's Tubes." The present paper gives an account of some researches undertaken by the writer along with Dr. Winkelmann to account for the origin of the different kinds of spectra, the band spectrum, the line spectrum, and the continuous spectrum. The spectrum experimented on was that of nitrogen, the media being air, hydrogen and oxygen respectively. The next paper is an abstract of a memoir by Prof. Lemström, of Helsingfors University, on the intensity of the flow of a voltaic current, which is followed by one in the department of acoustics, by J. J. Oppel, on two remarkable circumstances in connection with what he in a former paper called "Reflexionstone" or "Gittertone." The next paper is the first portion of the second part of Herr W. Sellmeier's paper on the subject of the vibration of molecules, which is followed by the continuation of E. Ketteler's elaborate memoir on the influence of astronomical movements on optical phenomena. The next paper is an attempt by L. Lorenz, of Copenhagen, to discover the means of determining in absolute terms, degrees of heat, and to show more clearly the relation in which heat and electricity stand to each other, which is connected to some extent with the paper which follows by S. Subic, on temperature constants. A few short papers conclude the number.

No. 12. The first article in this number is a long one by Dr. R. Börnstein, on the theory of Kühmkorff's induction apparatus, which is followed by the conclusion of the second part of Sellmeier's paper on the vibration of molecules. The next article is a criticism, by F. C. Henrici, on a paper read by Tomlinson to the Chemical Society, on the action of solid bodies on supersaturated solutions. E. Reusch contributes an article on the doctrine of twin-crystals, and J. Hervert one on transverse vibrating flames. V. Dvorák contributes an account of some experiments to test Airy's theory of the Talbot bands. Among the shorter papers is one by F. Zöllner on the reversion spectroscope.

Mittheilungen der Naturforschenden Gesellschaft in Bern aus dem Jahre, 1871.-The first part of this goodly sized volume is occupied with the proceedings of the Scientific Society of Bern for 1871. The following are some of the longer papers which make up the bulk of the volume. The first is the continuation from a former volume of Dr. Cherbuliez' Historical Résumé of Researches on the rate at which sound is propagated through the atmosphere; the same gentleman contributes some historical notices concerning the mechanical theory of heat. Considerable space is given to the continuation and conclusion of Dr. H. Wydler's contributions to a knowledge of the indigenous plants of Switzerland; and L. Fischer contributes a long list of the cryptogamic plants to be found in the neighbourhood of Bern. One of the longest and most interesting articles is by E. Schaer, being contributions to the chemistry of the blood and of ferments; the first part treating of the influence of cyano-hydrogen and phenol on certain properties of the blood corpuscles and various ferments; and the second part on the action of cyano-hydrogen and phenol on yeast and on mould-fungi. This is followed by a paper by Dr. A. Forster on the colouring of smoky quartz or topaz. The concluding paper in the volume, which is accompanied by a well-constructed map and graphic tables, is by A. Benteli, who attempts to estimate the amount of moisture precipitated by the atmosphere in the seven chief river-districts of Switzerland. The volume is altogether highly creditable to the Society whose transactions it records.

Some months since, he said, I communicated to the Royal Society the result of observations on y Draconis made with the water-telescope of the Royal Observatory (constructed expressly for testing the quality of the coefficient of sidereal aberration, whether the tube of a telescope be filled with air, as usual, or with water) in the spring and autumn of 1871. Similar ob servations have been made in the spring and autumn of 1872, and I now place before the society the collected results. It will the uniformity of results for the latitude of station necessarily be remembered, from the explanation in the former paper, that proves correctness of the coefficient of aberration employed in Apparent Latitude of Station

the Nautical Almanac.

I now propose, when the risk of frost shall have passed away, to reverify the scale of the micrometer, and then to dismount the instrument.

Mathematical Society, Jan. 9.-Dr. Hirst, F. R.S., president in the chair.-Papers were read by Mr. S. Roberts, V.P., on parallel surfaces; Prof. H. J. S. Smith, on the greatest common divisors of the minor determinants of a rectangular matrix of which the constituents are integral numbers, and on an arithmetical demonstration of a theorem in the integral calculus (these two communications were founded upon a paper by the author, published some few years since in the "Philosophical Transactions." Prof. Wolstenholme, on the summation of certain series (read in the author's absence by the secretary). This was concerned with the obtaining of a series closely related to Vandermonde's well-known series,; thus, Vandermonde's series beingn (n − 1)

(a + b)2 = b2 + n b1 −1 a1 +

I 2

then the series discussed might be writtenn (n − 1) (a + b)n b1 + n (b − 1 ) − 1 1 +

+

2

n(n − 1) (n − 2) (b−3) −3(a + 2)3 + -3 + (a + n − 1)n 3 Amongst the presents received were three War Department weather maps, Signal Service, U.S. army, Washington, Friday, November 22, 1872, constructed for 7.35 P.M., 4.35 P.M., and

II P.M.

Chemical Society, Dec. 16, 1872.-Prof. Frankland, F.R.S., president, in the chair.-"Notes on various Chemical Reactions," by Dr. Davies, contained observations on the formation of the sulphides of copper and barium, also some notes on the separation of nickel and cobalt.-Mr. H. Grimshaw communicated the results of his researches on ethyl-amyl and its deri vatives. After the president had made some remarks on the thoroughness with which this research had been carried out, a communication from Dr. Schorlemmer on "The heptanes from Petroleum,' was read. This paper contained, among other matter, an interesting account of the separation of isomeric heptylenes by means of hydrochloric acid.-A paper by Mr. T. Cornelley on the "Vanadates of Thallium," was then read. It contained descriptions of several new and complex vanadates of Thallium. Mr. Kingzett communicated to the society the results of his experiments on the conversion of sodium chloride into sodium sulphide by the action of hydrosulphuric acid; and finally, Mr. P. Braham exhibited some ingenious apparatus which he had arranged for the prosecution of physical researches under the microscope.

Photographic Society, Jan. 14.-James Glaisher, F.R.S., president, in the chair.--The President delivered a lecture on the application of photography for registering magnetical and meteorological phenomena, pointing out that no other method of registration was sufficiently delicate for the purpose; the lecturer explained that the magnetical records were obtained by a mirror arrangement fitted to the moving magnet, and in this way a pencil of light was reflected upon sensitive paper wound round a cylinder, which revolved once in twenty-four hours, thus securing a wave line representing the magnetical currents of the earth during the day. Meteorological records required less complicated apparatus. The photo-chemical process employed was also explained. Dr. E. J. Gayer read a paper "On In

s'antaneous micro-photography," and exhibited pictures of live animalculæ in water.-Dr. E. J. Gayer also read a paper "On a cause of fading in albumenised pictures."

PARIS

Academy of Sciences, Jan. 6. This was the annual general meeting of the Academy, and M. Faye, after delivering an address mainly devoted to the transit of Venus expeditions, vacated the chair, where he was succeeded by M. de Quatrefages.-M. Le Baron C. Dupin read a note on the French popu. lation, which, allowing for the ceded provinces, shows a decrease of 1,279,451. The decrease the Baron asserts to have been directly and indirectly caused by the late war.-M. Boussingault gave an account of his experiments on the formation of nitric compounds by the soil. He finds that these bodies are not formed from the nitrogen of the air, as he had been inclined to think.-M. A. de Caligny read an interesting paper on the effects of certain kinds of waves on sand-banks. Further observations of 128 by M. Borrelly were received, and also M. Bossert's Elements and Ephemerides of the same planetoid.-A paper on orthogonal surfaces, by M. G. Darbonn, was then read, and followed by an answer to M. Gernez's criticisms by M. G. Van der Mensbrugghe, who defends his and Mr. Tomlinson's theory of the action of films on saturated solutions.-A note on certain phosphorous compounds, in which that body appears to exist in the amorphous (red) form, by M. A. Gautier followed.-M. A. Houzeau sent a paper on the estimation of ammonia in coal gas.-MM. Estor and Saint-Pierre sent a short note on respiratory combustion. They have made experiments which prove intra-arterial as against pulmonary combustion.-M. Sanson sent a paper on the horse of the quaternary fauna, which was followed by a note by M. Diamilla Müller on the absolute magnetic declination at Tiflis, at Sevrova, and at Paris.-M. de Rouville sent a paper on the upper Jurassic formations of the department of L'Herault.

M.

January 13. M. de Quatrelages, president, in the chair. Jamin presented his fourth note on a magnetic condenser, a description of an apparatus he has contrived, by which the power of magnets is much increased.-M. E. Mouchez read a note on the rising of the Algerian Coast.-M. H. Resal sent a note on Savart's observation of the mutual influence of two pendulums.-MM. Troost and Hautefeuille read some researches on the Allotropic forms of phosphorus; they point out the similarity of the changes of vapour density in phosphorus when undergoing allotropic modification to those of cyanic; they also state that the sudden development of heat in the case of phosphorus when at the point of change has an exact analogy in the case of the acid mentioned.-MM. F. Bagault and Roche sent a note on a new process for the manufacture of steel. The process consists of decarbonising cast iron by means of rich iron oxide ores. -An interesting mathematical paper on orthogonal surfaces was received from M. G. Darbown.-M. Gernez controverts some assertions of Van der Mensbrugghe as to the effects of liquids of high surface tension on liquids of low tension. Van der Mens

brugghe asserts that when such liquids are in contact, if the first contains a dissolved gas it is compelled to liberate it.-M. Melsens sent a note on sulphurous and chlorosulphuric acid and on the combination of chlorine and hydrogen in darkness. The author saturated charcoal with chlorine, and then introduced it i to an atmosphere of hydrogen. The two gases completely and quietly combined in absolute darkness.-M. Prenier sent a note on "Polypropylenic Carbides." These bodies are formed by acting on propylenic bromide by nascent hydrogen; their general formula is C2H2.-M. J. Chaulard sent a note on the spectroscopic examination of the chlorophyll in residues of digestion. This body does not seem to be broken up in the stomach, as its absorption bands are distinctly recognisable in the excrements of animals fed on vegetables.-M. Stan. Meunier sent a note on "The increase of mechanical forces in the star (now destroyed), from whence the meteorites are derived.-M. P. Fischer sent a note on the Jurassic formations of Madagascar.-M. Pisani sent a paper on the analysis of Lanarkite from Leadhills, Scotland; he asserts that the mineral is a basic lead sulphate.-M. Chapelas's note on the aurora of January 7, was then read, and followed by a note from M. Poirée, oa tae levelling of the zero of the flood gauges of the Seine.-A letter from M. P. Bert to the President concerning M. Faye's recent defence of the Bureau des Longitudes was next read. M. Bert says that he did not propose the total suppression of the Bureau, but that he said that as it had not swered the expectations of science, it ought to be replaced by

a bureau whose duty (like that of the "Nautical Almanac office in England), would be to publish the Connaissance des Temps, and this office should receive not more than 40,000 francs (per annum ?)

DIARY

THURSDAY, JANUARY 23.

ROYAL SOCIETY, at 8.30.-Contributions to the History of the Orchins: Dr.
Stenhouse On the Fossil Mammals of Australia: Prof. Owen.—Notes
on the Wide-slit Method of Viewing Solar Prominences: W. Huggins.
ROYAL SOCIETY CLUB, at 6.

ROYAL INSTITUTION, at 3.-On Oxidation: Dr. Debus.
SOCIETY OF ANTIQUARIES, at 8. 30.-Implements of the Bronze Period: Jahr
Evans.
FRIDAY, JANUARY 24.1

ROYAL INSTITUTION, at 9.-Analogies of Physical and Moral Science: Prol.
Birks.

PAMPHLETS RECEIVED

ENGLISH.-Scottish Naturalist, Vol. ii. No. 9.-Fond Journal, Vol iii. No. 36. American Journal of Science and Art, Nos 24, 25, for Dec. 1852 and Jan. 1873.-The Astronomical Almanack, 1873: W H. Hollis (Simpkin and Marshall). Zoologist, No. 88.-Entomologist, No. 112.-Sermocas in Sonnets W. Whale.-Proceedings of the Zoological and Acclimatisatica Society of Victoria, and Report of the Annual Meeting of the Society, held March 1, 1871, Vol. i-Fifth Annual Report of the Executive Committee of the Manchester National Society for Women's Suffrage. Journal of the Royal Horticultural Society of London, Part 11, 12, Vol iii. 1873-Practical Magazine, No. 1. 1873.

AMERICAN-The Lens, Vol. i. No. 4.

FOREIGN.-Rendiconti, Vol. v. No. 19 -Bulletin de la Société Imperial des Naturalistes de Moscow.

Moon's Surface.-C. H. W. MERLIN.

The Twinkling of the Stars.-Dr. G. F. BURDER
Logarithmic Tables.-Prof. ASAPH HALL
Will-o'-the-Wisps.-HOWARD Fox.

Spect oscopic Observations.-E. W. PRINGLE.
GEORGE CATLIN

ON THE OLD AND NEW LABORATORIES AT THE ROYAL INSTITUTION.
By WILLIAM SPOTTISWOODE, Treasurer R.S. and R I.
PROFESSOR TYNDALL IN AMERICA

ON THE SPECTROSCOPE AND ITS APPLICATIONS, II. By J. NORMAN
LOCKYER, F.R.S. (With Illustrations.)
SCHOLARSHIPS AND EXAMINATIONS FOR NATURAL SCIENCE AT CAM
BRIDGE, 1873.

NOTES ON ZOOLOGY AND BOTANY IN LISBON. By H. N. MOSELEY

NOTES.

STAR SHOWER SEEN AT MAURITIUS. By C. MELDREM SCIENCE IN ITALY By W. MATTIEU WILLIAMS, F C.S. SCIENTIFIC SERIALS

SOCIETIES AND ACADEMIES

BOOKS AND PAMPHLETS RECEIVED. DIARY

There appear to be many advantages in this new form of measuring bar, of a geometrical, mechanical, thermal, and economical character. Much importance is attached to the absolute uniformity of the bar throughout its whole length, as equalising its resistance and molecular action, and also to the adoption of a geometrical form as symmetrical as possible. The absence of any acute angle was also dwelt upon as facilitating the mechanical displacement of the surplus metal; and it has since been practically ascertained that the planing can be executed with the utmost regularity and precision. It will also prove an excellent test of the soundness of the metal throughout the whole length of the bar. The great rigidity of this form of bar, combined with the advantage of the high elasticity of the platinum-iridium, was fully shown; as compared with the rigidity of the Mètre des Archives, it will be as 25'9 to 1, although its sectional area is only half as much more. The new form will also be highly favourable for equalising the temperature throughout its whole length and thickness, and for taking the temperature of the surrounding medium; and it will afford a most convenient lodgement for mercurial thermometer tubes, thus enabling the actual temperature of the measuring axis of the bar to be readily and accurately determined. This measuring axis will be in one open and unbroken line, and quite unaffected in its dilatation by any contact with the support of the bar. Lastly, in an economical point of view, the form proposed will give the greatest possible strength with the least quantity of the costly material used.

determination of the temperature by thermometers will be requisite. The question of the amount of dependence to be placed on the indication of the temperature by mercurial thermometers, which has recently been a good deal agitated in this country, was considered by the Commission to be one of great importance. They found that in all mercurial thermometers, the dilatation of the glass envelope, which, so far as it is known, is only about oneseventh that of the quicksilver, renders the reading of the best calibrated thermometers liable to errors amounting to some tenths of a centesimal degree. The best authorities are also of opinion that implicit dependence cannot be placed on the constancy of mercurial thermometers, so far as they indicate the temperature, nor on the constancy of the dilatation of the glass envelope. It was thought, therefore, that for ascertaining the temperature with a degree of precision exceeding o° C., recourse must be had to an air thermometer.

On the other hand, the air thermometer is an instrument complicated in construction and difficult to use. It requires the greatest precautions and practised skill in its manipulation; and the necessity of having recourse to an air thermometer on every occasion of making comparisons with the primary standards would create very serious embarrassments. On these grounds it was decided that every one of the new metres should be accompanied by two detached mercurial thermometers, carefully compared with an air thermometer, and which should be reverified with it from time to time.

It was stated to the Commission by M. H. Saint-Claire Deville, as the result of twenty years' use of an air thermometer, that no instrument could be more precise and convenient in reading, more easy and expeditious in use, He estimated that by employing an air thermometer according to a method suggested by him, the mean tem

determined with precision to theth of a degree of the centigrade scale.

On the subject of dilatation, we can only briefly allude to M. Fizeau's admirable method of accurately determin

The temperature at which the new metre will have its true length has been decided to be the same as that of the Mètre des Archives, that is to say, o° C. All the necessary arrangements have been already made for making comparisons at this temperature by constructing a cold chamber expressly for the purpose, and surrounding it with non-conducting materials. By a blast of cold air driven by a steam-engine in an adjoining room over a surface of ether and through pipes into the cold chamber, the temperature in it may be reduced in a few hours to the freezing point, and maintained constant there. From this adjoining room also the requisite light is conveyed into the cold chamber, an l is thrown by reflection on the bars and apparatus. There is an inner part of the chamber in which the standard metres and the comparing apparatus are placed, whilst the observer is enabled to mike the adjustments and the comparisons through the microscopes from an outer part, and thus the heat of his body is prevented from exerting any disturbing influence on the bars and apparatus.

Many comparisons of the metre will, however, be made at other temperatures, and in all such cases, as well as for

ploying the length of a wave of monochromatic sodium light (a constant = 0005888 millimetre, or o'00002318 inch), as his standard of measure. By means of an ingenious apparatus constructed by M, Soleil, the yellow ray is made to fall vertically through a piece of plate glass on a horizontal plane of the solid body, and is reflected in the under-surface of the glass. By counting the number of Newton's rings passing a fixed point upon the glass, when they are set in motion from the expansion of the surface of the solid body by observed degrees of heat, its dilatation can be computed with the greatest precision. This method has been described in the proceedings of the Royal Society on November 30, 1866, when the Rumford gold medal was awarded to M. Fizeau for it. The Commission also hope to obtain a standard of dilatation by marking a measure of length of one or two decimetres upon the plane surface of a piece of Beryl in its axis of non-dilatation. M. Fizeau has shown that Beryl varies in its dimensions from heat less than almost any other body, and that it possesses this peculiarity, that whilst it expands by heat in the direction of its axis of crystallisation, it contracts by heat in the direction perpendicular to