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rial and to protect the user from carelessness or fraud. But it has also acted as a stimulus to manufacturers to standardise and improve their products. Once it is known how good a quality can be produced, all manufacturers strive to reach it, and the average quality is raised. The rapid development of cement and of the higher qualities of steel has depended on the determination of their superiority by accurate tests in the properties required for special services.

With the introduction of mild steel, the quality of which ranges between wide limits, the need of systematic testing became urgent. Now there are testing laboratories in the works of most railway companies and in steel works. Also the practice of testing has been adopted in the case of many other materials. With the extension of testing has come the need of standardising tests themselves, a work now largely accomplished by the International Association and the British Standards Committee. But with the increasing stringency of specifications, perhaps more attention should be given to the calibration of the instruments used in testing. In physical investigations great attention is given to the determination of the errors of instruments and methods, and perhaps in material testing this has received too little attention. I do not suppose there are important errors in the indications of large testing machines, though a comparison of results in different laboratories would be interesting. Errors in subsidiary apparatus are probably more frequent. It is possible with a standard bar and a good extensometer, used by the same practised observer to measure the agreement or disagreement of different testing machines. I have found also the use of copper cylinders subjected to crushing to be a very convenient means of checking load indications of machines.

On the Continent and in the United States there are public laboratories, supported by the State, where anyone can have tests made, at moderate fixed rates, by a trained scientific staff and with great accuracy. Such institutions assist industry if, on one hand, they meet industrial requirements, and, on the other, are unbiassed by private interests. They have the advantage over private laboratories that they are under the direction of experts of exceptional experience and reputation, and are able to pursue investigation, continued often for long periods, beyond immediate requirements into fruitful by-paths. The view taken in Germany is that the work accomplished is partly of advantage to the manufacturer who calls for assistance, and so far should be paid for by him, and partly is of advantage to the nation in advancing science, which is the justification for a State subsidy. Hence it is incumbent on the public institution to publish results as freely as is possible without injuring private interests.

At Grosslichterfelde the annual income from fees for testing amounts to 20,000l., and the annual State subsidy is 12,000l. On the staff there are 230 persons, of whom seventy-five have had university training and thirty-eight technical high-school training. Since 1880 the work accomplished has steadily and regularly increased.

The Bureau of Standards at Washington is on a still larger scale, and does very similar work. It receives an annual subsidy from the Federal Government of 100,000l. The equipment is extraordinarily complete. For instance, it has a 600-ton testing machine at Washington, and a 1000-ton testing machine at Pittsburgh, both of the highest sensitiveness and accuracy. Such machines do not exist in this country. Happily, we have now a similar institution in the National Physical Laboratory at Teddington. Its functions are somewhat restricted by the

characteristic English jealousy of State action, which I think is diminishing. It would be difficult to overestimate the service it has done in the solution of various mechanical, electrical, and physical problems which were unlikely to be attacked by private persons. Some of the researches started by this institution have been carried out there, and valuable papers contributed to our Proceedings. The superiority of English aeroplanes has been demonstrated, and their services for scouting and for directing artillery fire have been invaluable. When the Government required difficult experimental investigations to be carried out on aeroplanes, it found at Teddington a staff and an organisation already in existence and suited to the purpose.

It is a condition of commercial testing that the results should be available in a short time and at small expense. Hence ordinary tests are of a somewhat arbitrary character, and do not completely imitate the conditions of actual service. We test specimens of steel to destruction and measure ductility by plastic deformation, though in use the stresses do not exceed the elastic limit and the deformation is elastic. We test cement in tension and use it in compression. There is need for constant criticism of methods of testing and for the invention of new tests, such as tests for hardness and brittleness, although new tests must be cautiously introduced.

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One small change could be easily made, and in some cases would be interesting. When a set of tests on a material has been made, the mean of the results is taken as the best value of the property measured. In physical investigations generally a further step is taken by calculating what is termed the "probable error," which broadly is a measure of the trustworthiness of the results. Calculation of the probable error is troublesome, but Martens has pointed out that the mean error" is nearly as accurate, and good enough for practical purposes. The mean error is the sum of the deviations of the individual results from the mean, irrespective of sign, divided by the number of observations. The mean error is conveniently expressed as a percentage of the mean value. If the mean error is large, either the method of testing, the uniformity of the material, or the preparation of the test specimens is at fault. Generally the source of the error can be inferred. A large mean error in tests of steel would indicate want of uniform quality in the material, in cement-probably faults in preparing the test briquettes. Of two supplies of a material, that with the smallest mean error is preferable.

There is another kind of testing, likely in the future to be of increasing importance that is, the measurement of strains in members of completed structures in order to determine the stresses to which they are actually subjected in service. Some years ago, after the loss of the Viper, measurements of the strains in the skin of a torpedo-boat slung in various ways were made at the request of the Admiralty. The object was to obtain information on the stresses in a structure supported on waves. Strain measurements on the members of bridges during the passage of trains have been made in Holland, in France, by Mr. La Touche and Mr. Sales in India, and by Prof. Turneaure in the United States. These observations throw light on two points-the trustworthiness of theoretical calculations of the stresses and the magnitude of the stresses due to dynamical actions which cannot be calculated. Recently Mr. I. E. Howard, engineer-physicist at the Bureau of Standards, has initiated a very extensive investigation which is to extend to large bridges, the Panama lock-gates, and steel-framed buildings. Some results on the stresses in the shell of a simple cylindrical tubular boiler have been published. A cylindrical boiler shell is a very simple structure, and the straining

action is statical. It might be expected that theoretical calculations of the stresses would in that case be approximately verified by the observations. In fact it is not so. The distribution of stress is very much less uniform than it is assumed to be in theory and in the design of boilers. Of course, this is chiefly due to angle-irons and joints, which in most cases reduce the stresses, but, at any rate, greatly modify the stress distribution.



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GLASGOW.-The course of instruction in engineering for the B.Sc. degree is conducted upon the sandwich" system. Under this plan, the laboratory staff is occupied during the six winter months in providing the prescribed lectures and demonstrations for the students. During the months April to October the ordinary students obtain their practical training as pupils in the various engineering works of the district. In summer the laboratories are accordingly employed only for special forms of instruction and for research. This year, at the close of the winter session, Prof. Cormack and his colleagues-lecturers, assistants, demonstrators, and mechanics offered their services through the principal of the University to Lord Kitchener for any purpose connected with the production of munitions of war, which he might think fit to indicate. The Secretary of State, through the Master-General of the Ordnance, has cordially acknowledged the offer of the staff, and promises speedily to inform the University as to the manner in which it may be utilised to the best advantage. In the meantime, the Admiralty has, with the sanction of the University Court, made arrangements for using the equipment of the laboratories, and in particular of the testing machinery, for the purpose of testing the specimens of steel and other metals employed by the contracting firms who are manufacturing shells, etc. Prof. Cormack and Mr. Morley, lecturer on heat engines, have undertaken to supervise the operations under the direction of the Admiralty inspector. large proportion of the engineering students, who completed their course at the graduation in April, have found places in the munition factories.


LONDON.-Among the public lectures, which are open to the public without fee, to be delivered at University College, during the present term, are the following:-April 29: Prehistoric Egypt, Prof. W. Flinders Petrie; April 30: Serbian ideals, Miss Annie Christitch; May 3: The principles of technical evaporation and distillation, Dr. W. A. Caspari; May 4: Hindu religions, Prof. L. D. Barnett.

OXFORD.-Prof. J. Mark Baldwin, honorary professor of the University of Mexico, formerly professor of philosophy and psychology in the Johns Hopkins University of Baltimore, has been appointed Herbert Spencer lecturer for the year 1915-16.

ACCORDING to the Korr. Norden, lectures in the University of Berlin will be greatly reduced, on account of the number of professors and students at the front.

WE learn from Science that under the will of the late General Charles H. Pine, recently published, Yale College will eventually receive an addition of 30,000l. to the 10,000l. scholarship fund established by General Pine about three years ago. The will also provides for the creation of a fund of 50,000l. to be devoted to manual training of Ansonia boys and girls. From the same source we learn that by the will of General William D. Gill, of Baltimore, the Johns Hopkins University is made residuary legatee after the death

of his wife. The bequest is to be used for the estab lishment of a chair of forestry. The sum of 5000l. has been contributed by Mr. P. S. du Pont toward the University of Pennsylvania Museum extension building fund, which now amounts to more than 20,000l. As soon as the fund amounts to 100,000l., the building of the next extension will be started.

THE Civil Service Estimates for the year ending March 31, 1916, include a vote of 145,000l. for special grants in aid of certain universities, colleges, medical schools, and agricultural institutions, to meet loss of income arising during the war. It is pointed out that certain of the universities, colleges, and other similar institutions which are in receipt of Parliamentary grants have been adversely affected by the war, more especially by the loss of fee income arising from the widespread response among men students to the call for recruits. The special grants in aid will be used to give such assistance as may be necessary to save the institutions in question from suffering serious permanent detriment from the temporary emergency. The expenditure of the universities, colleges, and other institutions out of the grants will not be accounted for in detail to the Comptroller and Auditor-General, nor will any unexpended balances be surrendered by the payees at the close of the financial year.

College, has recently been appointed official lecturer DR. H. B. GRAY, formerly headmaster of Bradfield at the Imperial Institute in order to give short lectures on the resources of the countries of the Empire, illustrated by the collections of exhibits which are to be seen in the various courts assigned to those countries in the public exhibition galleries of the Institute at South Kensington. Since the beginning of last month a succession of such lectures has been delivered at the institute by Dr Gray, chiefly to schools in London and its neighbourhood, in connection with the school teaching of the geography of the Empire. In addition to these lectures to schools, it is now intended to arrange a weekly lecture in the exhibition galleries, of a less formal kind, for members of the general public in connection with the exhibits illustrative of the present condition and resources of the Colonies and India. The first of these lectures will be given on Wednesday, May 12, at 3 p.m., on Canada and Newfoundland, and will be followed each week in May on Wednesdays, at 3 p.m., by short illustrated lectures on other countries of the Empire in turn. A separate announcement will be made with regard to the lectures in June. charge will be made for these lectures. Admission will be by ticket, to be obtained at the Imperial Institute, South Kensington. The number attending each lecture will be limited to fifty.


THE Journal of the Institution of Electrical Engineers contains an interesting paper and discussion on training for the industrial side of engineering. The paper is by Mr. A. P. M. Fleming, who described the apprentice school which the British Westinghouse Company established a year ago at their own works. Instruction averaging about five hours a week is given during working hours to all bound apprentices, numbering altogether about 300. The regular rate of wages is paid during the time spent in this way, and the cost of books and stationery is also defrayed. Teaching is done by twelve members of the engineering staff, supplemented by lectures from the leading foremen and shop engineers. Ten of the most promising apprentices are selected each year and sent for one whole day a week to the course for engineering apprentices at the Municipal School of Technology, Manchester. Mr. Fleming emphasised the unsuitability of the evening classes in most industrial centres for "trade" instruction, which he thought

was of comparatively little use to the youth who would be a workman all his life. On the other hand, he considered evening technical instruction excellent to give youths possessing ability and determination a means of rising from non-technical to technical employment. Prof. E. W. Marchant endorsed what Mr. Fleming had said with regard to evening classes, and said that it seemed to him a physical impossibility for a man engaged in manual or other labour during the day time to study effectively if he gets his technical education in the evening. On the other hand, Prof. Miles Walker, of the Manchester School of Technology, said that although day classes were better for those who could attend them, as the students would be fresher and better able to utilise their faculties, yet the men who came after their day's labour was over and did really good work three evenings a week with home lessons on Saturdays and Sundays must possess admirable qualities. Mr. J. Collinge referred to the difficulty of training young engaged in central stations, who had not been able to afford college training, as owing to the character of the work and the hours they had to be employed they were largely prevented from regular attendance at technical schools, and consequently frequently found themselves in a "blind alley."



Royal Society, April 22.-Sir William Crookes, president, in the chair.-Lord Rayleigh: Deep water waves, progressive or stationary, to the third order of approximation. The principles of hydrodynamics are applied to form the equations of wave-motion to the third order of approximation without restriction other than that the motion is irrotational and in two dimensions. The results are then applied to the progressive wave of permanent form, as investigated by Stokes, and to stationary waves. It appears that the form of the latter at the moment of greatest deviation from mean level is the same as that of the permanent progressive wave, but that the periods of vibration corresponding to the same wave-length are different.-Hon. R. J. Strutt : A chemically active modification of nitrogen, produced by the electric discharge. VI.-Dr. C. Chree: The difference between the magnetic diurnal variations on ordinary and quiet days at Kew Observatory. The paper considers the difference between the diurnal variations of magnetic force at Kew Observatory on quiet days and ordinary days (i.e. all days with the exception of those of large disturbance). The data employed are from the eleven years 1890-1900. Taking mean data for the whole year, the difference in the horizontal plane may be regarded as consisting, to a first approximation, of a harmonic oscillation of twenty-four hour period along a direction inclined 64° east of north and of a regularly progressive noncyclic change in a second direction which is perpendicular to the former. The result, while true of the days of the year as a whole, is only imperfectly exhibited in most individual months.-F. Horton: The effects of different gases on the electron emission from glowing solids. An investigation has been made of the ionisation produced by a glowing Nernst filament when used as a kathode in a discharge tube in the presence of various gases of different chemical affinities for the material of the filament. It has been found that the actual electron emission from the filament is independent of the nature of the surrounding gas, at least for the gases, air, nitrogen, oxygen, and hydrogen, for at low pressures the thermionic currents measured under similar conditions in these gases were

practically the same. At higher pressures the thermionic currents differ considerably owing to the effect of ionisation by collisions being different in the different gases. The increase in the current due to ionisation by collisions in hydrogen is much greater than it is in air, oxygen, or nitrogen. The experiments were repeated with a Nernst filament covered with lime, and it was similarly found that the electron emission from lime under these conditions was not increased by hydrogen, although earlier experiments have shown that lime heated on platinum gives a much larger electron emission in hydrogen than it does in air. This appears to be caused by the hydrogen increasing the emission from the platinum, an effect which has been shown by H. A. Wilson to be due to the absorption of hydrogen by the metal. Lime and the oxides of a Nernst filament do not absorb hydrogen, and the electron emission from these substances is therefore unaltered by the presence of this gas. That the electron emission from an oxide kathode is the same in oxygen and in hydrogen, gases which have very different chemical affinities for the material of the kathode, is evidence against the theory which has lately been put forward, that the electron emission from a glowing solid is due to chemical action between the solid and the surrounding gas.-W. S. Tucker : Heats of dilution of concentrated solutions. More detailed study of the variation of heat of dilution with concentration is here described than has hitherto been published. Dilution was performed by short steps by addition of water at air temperature. Specific heats of solutions were accurately obtained for various concentrations so that heats of dilution could be calculated and lithium chlorides and sodium hydroxide give for any mean concentration. Solutions of hydrogen results which appear to show a linear relation with mass concentration, for the range over which heat of dilution has an appreciable magnitude. Curves are shown which indicate that this heat of dilution, if that linear relation be accepted, will vanish at such concentration as will suggest the formation of some simple hydrate of the solute. Thus the straight line connecting heat of dilution and mass concentration for hydrochloric acid solutions will, if produced, cut the axis of concentration at HC1,15H2O. Solutions of lithium chloride and sodium hydroxide similarly yield hydrates LiC1,8H2O and NaOH,SH2O.-T. R. Merton : The origin of the " 4686" series. An attempt has been made to obtain some information as to the origin of the "4686" series by measurements of the relative breadths of the "4686" line and the helium lines, from which the relative masses of the atoms concerned can be calculated according to the relations which have been found by Lord Rayleigh, Michelson, Buisson and Fabry, and others. The conclusion arrived at is that either the breadth of the "4686" line is controlled by circumstances at present unknown or that the line originates from systems of subatomic mass.

Zoological Society, April 13.—Mr. E. T. Newton in the chair.-E. Gibson: The Nato cattle of the Argentine. The author exhibited the skull and a photograph of some specimens formerly in his possession which he believed to be the last of the breed.-Dr. G. E. Nicholls : The Urostyle (Os Coccygeum) of the anurous Amphibia.-G. A. Boulenger: The snakes of the Belgian and Portuguese Congo, Northern Rhodesia, and Angola. The paper contained a list of all the species known to inhabit this region, with keys to the identification of the genera and species, and the descriptions_of_two new forms from Angola and Katanga.-Dr. R. Broom: Some new carnivorous Therapsids in the collection of the British Museum. Most of the specimens described have been for many years in the collection, but owing to their small size

and imperfect condition they have not hitherto been recognised as new. Five species, belonging to four new genera, are Therocephalians. Two species, one of which belongs to a new genus, are Gorgonopsians, and one is a new species of a previously known Cynodont genus.-Dr. R. Broom: The organ of Jacobson and its relations in the "Insectivora" Tupaia and Gymnura. Gymnura is shown to have the same type as is found in Erinaceus, Sorex, and Talpa, and most higher Eutherians such as Felis, Lemur, Miniopteris, Ovis, Bos, Equus, Procavia. Tupaia, on the other hand, has, like the allied Macroscelides, the primitive marsupial type. Peters and Haeckel in 1864 and 1866 had suggested separating Tupaia and Macroscelides as a suborder of the Insectivora, but the condition of the nasal cartilages shows that the Menotyphla should form a distinct order, not even closely allied to the typical Insectivora.

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Linnean Society, April 15.-Prof. E. B. Poulton, president, in the chair.-C. F. M. Swynnerton: Experiments and observations on the interpretation of form and coloration in plants and animals. Foodpreference and other experiments were carried out over five years on insectivorous and (later) carnivorous, egg-eating herbivorous, and other animals, and numerous field-observations made. The work was attempted on a large scale and with every precaution, experiments on captive insectivorous birds checked (and confirmed), by a series of experiments on wild birds, and various objections to a selectionist view specially tested. Numerous deterrent defences were found definitely to exist; also the finest gradation from those species of animals and plants that are only eaten through hunger, to the few that an individual enemy will eat to repletion-point. This indicated that the need for distinguishability from pleasanter forms (apparent and otherwise) is, and has been, widespread, and, with the numerous mistaken attacks and unmistaken refusals witnessed, suggested a contributory explanation for "distinctiveness" and diversity generally. Wild fruits were also “graded" by their eaters, and preferences shown by insects and birds as between even their own flowers; insect-hunting bird-parties were watched on a few occasions visiting exclusively particular particular temporarily-infested species of trees; and the utilisation of appropriate characteristics by animals for intra-specific recognition was amply illustrated by field-observation. Thus distinctiveness" (and differentiation) may have been very widely selected in relation to "friends Abundant observation of unmistaken attacks on prey and the latter's reply thereto testified to the great importance of the procryptic and actively evasive defences and to the fact of their appropriate utilisation. Moreover, enemies were seen to return expressly to stationary prey that they had not been hungry enough



birds were witnessed. Discriminative action that might contribute to selection was actually observed at work, interspecifically (as in the preferences shown), and intraspecifically (in choice of largest available prey, destruction, or artificial entry of inconvenient ornithophilous flowers, and individual destruction through the inactivity of extra-floral nectaries).

Mathematical Society, April 22.-Sir J. Larmor, president, and afterwards Prof. Love, vice-president, in the chair.-G. H. Hardy: Note on Dirichlet's divisor problem.-Col. R. L. Hippisley: Note on a new form of closed linkage.-G. B. Mathews: Division of the lemniscate into seven equal parts.--Sir J. Larmor: The influence of the oceanic waters on the law of variation of latitude. The prolongation of the periodic time of the small free orbital motion of the pole over the earth's surface from 304 to 428 days has been recognised to be due to the centrifugal strain of the earth's rotation changing in step with the changing axis of rotation. This regular circular precession is found to be strongly disturbed by irregular surface displacements of terrestrial masses. But among these disturb ances the adaptation of the ocean surface to the changing axis ought not to be included, for being synchronous with the precessional motion it must affect its period, and so fundamentally alter it instead of merely disturbing it. It is roughly estimated that if the earth were elastically unyielding, the effect of the existing ocean would be to lengthen the period of free precession from 304 to about 332 days. The remainder of the actual increase to about 428 days would be, as now, ascribed to elastic centrifugal strain of the solid earth, and the necessary slight revision of current estimates of its yielding is made on this basis. The question is broached, What would be the course of history of a planet so nearly spherical that the incumbent ocean would destroy secular stability for all possible axes of rotation?


Royal Irish Academy, April 12.-Rev. J. P. Mahaffy, president, in the chair.-Rev. P. Browne: An integral equation proposed by Abel, and other functional equations related to it. The paper deals principally with the equation, G(t)f(tx)dt=g(x), where G and g are known functions, and f is to be discovered; a and b are constants. Abel gave this equation as a generalisation of the problem of the isochrone, stating he had solved it, but the solution does not appear in his published works. A solution is found involving integration along an infinite straight line in the plane of the complex variable. By extensions of the method, the equations,

for on first discovery, and the view that a special "G(x, t)f(tx)dt=g(x), [[[G(t,r) ƒ (tx, ry)dtdt=g(x,y),

handicap may prohibit conspicuousness in a group, a species, a stage, or a sex was confirmed otherwise too. That it is through the existence or development of suitable counter-agents (as flight, nauseousness, procryptic underside, and special habits) that whatever factors make for conspicuousness have been together enabled (in another species, sex, etc.) to produce it, was shown; and several such factors were indicated, including sexual selection. Animals were deterred by resemblances in prey, and a double potential basis for mimicry was found definitely to exist; also a basis for synaposematism (in flowers synepisematism) in the observed effect of the more numerous reminders and simplified recognition that a link in appearance or smell would afford. Probable cases of mimicry were seen and tested in plants, eggs, and birds. More than 800 attacks on butterflies by wild

and others, are solved.-A. J. Rahilly: Some geometrical determinants. The geometrical determinants dealt with are of the type exemplified in Frobenius's theorem connecting the mutual powers of two quintets of circles. It is shown by a very simple method that similar determinantal relations exist between many sets of geometrical entities; in fact, a large part of the metric geometry of the point, line, circle, plane, and sphere may be reduced to such determinantequations. Some new applications are given; in particular, Ptolemy's theorem, which is a special case, is given several extensions.

Royal Dublin Society, March 23.-Prof. W. Brown in the chair.-Prof. J. Wilson: Simplified solutions of certain Mendelian problems in which factors have inseparable effects. The author makes use of two

simple observations to prove certain problems discussed in a previous paper on unsound Mendelian developments. The observations are:-(1) If one o more groups in a set of hybrids' progeny carry a character outside those producing the set, that character is common to all the groups in the set. For instance, if the characters carried by the four following groups have been found as set down, namely: agouti, 9XY; cinnamon agouti, 3 Xy; black, 3xYZ; chocolate, xy; then the character Z is carried by the three remaining groups, for otherwise black would differ from agouti and chocolate in more than one pair of characters, and from cinnamon agouti in more than two. (2) A character carried by more than half the groups in a set of hybrids' progeny is common to all the groups in the set. For instance, if the characters of three of the four groups in a set have been found as follows: agouti, 9XYZ; dilute agouti, 3; black, 3xYZ; blue, 1xYz; then dilute agouti must also carry Y, and, by the symmetry of the set, the additional characters X and z.-Miss A. Wilson Changes in soils brought about by heating. The increased productivity of soil which has been subjected to different degrees of heat has been studied by E. J. Russell and F. J. Seaver and E. D. Clark. Russell suggests that the increased productivity is due to the increase in the number of nitrifying bacteria consequent on the destruction of the larger organisms by heat. Seaver and Clark and others maintain that the heated soil owes its greater productivity to the increased amount of soluble matter due to the decomposition of soil constituents. these experiments extracts of suitably prepared soil heated to various temperatures between 60° and 150° during periods of two hours were obtained. The depression of freezing point and the electrical conductivity of each solution were then determined. It was found that there was a marked range in the coloration of the solutions thus obtained, and each solution gave a marked reaction to litmus. amount of water retained by the heated soil was also noted in one set of experiments, and found to increase with the temperature to which the samples were heated. Throughout the experiments the depression of freezing point and electrical conductivity showed a marked increase in the solutions obtained from samples heated at the higher temperatures.




Academy of Sciences, April 19.-M. Ed. Perrier in the chair.-A. Müntz and E. Lainé: Studies on the agricultural value of the sediments carried by the watercourses of the Alps and Pyrenees. From the chemical point of view, these sediments have nearly the same proportions of fertilising materials as good average arable soils. They vary greatly in physical properties and measurements were made of the apparent density, porosity, capacity for water, and permeability of sediments from different sources. The permeability varies greatly, and the fine sediments tend to choke the irrigated soil. Experience has shown agriculturists making use of irrigation the best means of dealing with this tendency to impermeability.-C. Guichard: A series of surfaces and the equations of Laplace which are reproduced by a transformation (m, n) of Darboux.-V. Grignard ́ and Ch. Courtot: Benzofulvanol and benzofulvene. Starting with the magnesium compounds of cyclopentadiene, indene, and fluorene, and treating these with aldehydes and ketones, secondary and tertiary alcohols are obtained which have been named fulvanols, benzofulvanols, and dibenzofulvanols, and these, by dehydration, give the corresponding hydrocarbons. The preparation is described of the benzofulvanol obtained from indene magnesium bromide and trioxymethylene and the

hydrocarbon benzofulvene obtained by its dehydration. M. Riquier: Partial linear systems composed of equations equal in number to those of their unknown functions. Rodolphe Soreau: Circular anamorphosis. -Pierre Humbert: The piriform figure of equilibrium of a fluid mass. Prof. Poincaré and Sir G. H. Darwin came to opposed conclusions as to the presence of points of inflexion on the section by a symmetrical plane of the equilibrium figure of a fluid mass in rotation. The author concludes that there are no points of inflexion and the calculations of Poincaré, pushed to the end, lead to the same result as those of Darwin.-B. Globa Mikhailenko: Modification of the ellipsoidal figures of equilibrium of a fluid mass in rotation under the action of capillary pressure.-M. Drzewiecki: Wind motors.-A. Leduc : The velocity of sound in gaseous mixtures. The application of a formula deduced in a previous communication to consideration of the velocity of sound in moist air, carbonic acid (Regnault's experiments), and mixtures of air and methane. The deviations between experiment and the author's theory are explained by the assumption that the latter is correct and that the gases used by Regnault and Capstick were impure.-Daniel Berthelot: The kinetics of photochemical reactions.Ch. Courtot: The theory of the oscillation of the indene double linkage. The theory put forward by Thiele to explain his experimental results is unnecessary, since owing to an isomeric change unperceived by him he was dealing with only one benzylindene, the y compound. The a-benzylindene has been prepared by the author, and is shown to be distinct.-M. and Mme. Fernand Moreau: Nuclear evolution and the phenomena of sexuality in the lichens of the genus Peltigera.-M. Fonzes-Diacon: Copper spraying fluids. The acid fluids have a high anticryptogamic action, the neutral and alkaline solutions are less active.


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