March 8, 1900] 



NATURE 



457 



partially supported themselves by work upon the College farm 

 during summer, and during the long winter vacation they taught 

 district schools, thereby earning enough to pay their expenses 

 at College. But conditions in Michigan have very much changed 

 since that time, and the long vacation is not now in winter, as 

 was formerly the case, but in summer. Students, who have not 

 learned the ordinary operations of farm work before entering 

 the College, have to spend one long vacation on the College 

 farm. As the College farm and park cover an area of 676 acres, 

 there is plenty of opportunity to study practical agriculture. 

 The report of the Experimental Station provides the students 

 and the farmers of the State with much useful information. 

 The influence which the Station exerts upon the agriculture of 

 the State may be estimated from the fact that more than 24,000 

 copies of the bulletins are distributed. These bulletins, which 

 deal with such subjects as "Sugar Beets in Michigan," "Ex- 

 periments in Corn Raising," " Commercial Fertilisers," " Bac- 

 teria and the Dairy," '• Feeding Dairy Cows," " Injurious j 

 Insects," and "Tuberculosis in Cattle," are in no wise com- 

 pilations, but records of results of original investigations ; their 

 value as a factor in the development of the agriculture of the 

 State must be very important. 



SCIENTIFIC SERIALS. 



American Journal of Mathematics, vol. xxii. No. i, 

 January. — Appareil a liquide pour I'integration graphique de 

 certains types d'equaiions differentielles, by M. Petrovitch, is a 

 continuation of the article, " Sur I'integration hydraulique des 

 equations dilTertntiellcs," by the same author (vol. xx. No. 4). 

 The article dtsciibes an apparatus, exceedingly easy to con- 

 struct, which gives a means of solving certain equations, 

 " integrables anaiyiiquement, mais il est commode pour les 

 applications d'avoir une methode rapide et sure pour la con- 

 struction mecanique de leurs courlies integrates " — The next 

 paper, proof that there is no simple group whose order lies 

 between 1092 and 2001, by G. H. Ling and G. A. Miller, con- 

 tinues the search begun by Holder, and carried on by F. N. 

 Cole and Burnside.— T. F. Holgate contributes a note additional 

 to a former piper on certain ruled surfaces of the fourth order. 

 The surface for which the nodal lines are real and distinct. 

 Fa*, and that for which the nodal lines are coincident, Fg*, were 

 previously discussed, but no mention was made of the surface 

 for which the nodal lines are imaginary, though the existence of 

 such a surface must have been in mind at the time. From the 

 geometrical standpoint a study of the separate surfaces is of 

 considerable interest. — H.F. Stecker's non-Euclidian properties 

 of plane cubics is an interesting discussion on the lines of 

 Clifford and Story.— Dr. E. O. Lovett gives two notes (i) on 

 the differential invariants of Goursat and Painleve, and (2) a 

 supplementary note on projective invariants (see the April 

 No. of the last volume). — Certain sub-groups of the Betti- 

 Mathieu group is a slight addition to a dissertation by Dr. L. 

 E. Dickson {Annals of Mathematics, 1897 ; (/. also the July 

 No. (1899) of the American yoiirnal).—\yT. W. H. Metzger 

 gives a brief note on the excess of the number of combinations 

 in a set which have an even number of inversions over those 

 which have an odd number.— On Lie's theory of continuous 

 groups, by E. W. Rettger, following up Study's and Taber's 

 work, investigates the two- and three-parameter 5ub-groups of 

 the general projective group in two variables, and of the general 

 homogeneous linear gioups in three variables, enumerated by 

 Lie on pp. 288, 5 1 9 of his Conlinuerliche Gruppen, and his aim 

 is to show that singular transformations occur among the trans- 

 formations of many of these sub-groups. — V. Snyder writes on 

 lines of curvature on annular surfaces having two spherical 

 directrices. Several interesting geometrical results are given. 



Symons's Monthly Meteorolo^^ical Magazine, February. — 

 Climatological records for the British Empire for 1898. Of the 

 eighteen representative stations from which observations are 

 regularly received, the highest shade temperature was recorded 

 at Adelaide, w^'^ on January 11, and the lowest at Winnipeg, 

 -34'''6 on December 31, with the greatest range in the year, 

 I26°'l, the least being at Grenada, i9°-8. The driest station 

 was Adelaide, mean humidity 59, and the dampest place, 

 ' lombo (Ceylon) and Trinidad, mean humidity 80. Adelaide 

 . registered the highest temperature in the sun, 173° 7. The 

 . atest rainfall occurred at Colombo, 103 i inches, and the 

 i(.ast, I5'6 inches, at Melbourne. The most cloudy place was 



NO. T584. VOL 61] 



London, the average amount being 6*4. The table shows a 

 remarkable similarity to that for 1897 ; there are only three 

 changes in the summary of extreme values. Malta, in 1898, 

 had a rainfall (292 inches) nearly ten inches alx)ve the average 

 of 15 years, and probably the greatest on record. 



SOCIETIES AND ACADEMIES. 

 London. 

 Physical Society. — Special meeting held by invitation of 

 Prof. Callendar in the Physical Laboratory of University Col- 

 lege, March 2.— Prof. G. Carey Foster, F.R.S., Vice-President, 

 in the chair. — Dr. F. G. Donnan read a paper on the relative 

 rates of effusion of argon, helium, and other gases. The intro- 

 duction to this paper contains a short account of the work which 

 has been done on the effusion of gases. This is followed by a 

 theoretical investigation of the subject, upon the assumption 

 that the ideal gas laws are obeyed, and that the back pressure 

 never rises above a certain fraction of the internal pressure. 

 This gives rise to formulae which are different from the square 

 root of the density law of Graham. The formula derived from 

 Hugoniot and Reynold's work gives the ratio of the limes of 

 effusion of two gases whose specific heat ratios are I 408 and 

 I •67, equal to i 06 times the square root of the ratio of the 

 densities. The constant derived from Parenty's work is i 084. 

 The theory therefore indicates that argon should effuse faster 

 than would be calculated from Graham's law. The gases used 

 were oxygen, hydrogen, nitrogen, carbon-mon-oxide, carbon-di- 

 oxide, cyanogen, argon and helium, and they effused through 

 small holes pierced in platinum foil. When the holes are large 

 compared with molecular dimensions the phenomenon is one of 

 efflux on a small scale. In the actual experiments this was the 

 case, although the holes were sufficiently small to cause 

 appreciable viscosity effects. By employing two or more 

 observations in conjunction with the relative viscosities of the 

 gases used, an apparatus constant was determined which allowed 

 these effects to be eliminated. The observations showed that 

 argon effused 3J per cent, faster than as calculated from the 

 densities alone. This agrees qualitatively with theory, 

 and affords a confirmation of the high specific heat 

 ratio of argon. Hydrogen, oxygen and carbon-mon-oxide 

 effuse in the manner predicted by the theory for gases having 

 the same, or nearly the same, specific heat ratios. Carbon-di- 

 oxide when compared with oxygen appears to effuse I per cent, 

 faster than as calculated from the densities. This result is not 

 in accordance with the adiabatic theory of the efflux of ideal 

 gases. The results for helium are not uniform, but show that 

 its behaviour is unlike that of argon, a result not foreseen by 

 the theory. If account be taken of the deviation of ordinary 

 gases from the ideal laws, it is possible to obtain an expression 

 for the efflux which contains a correction term involving the 

 constant K of the Joule-Thomson effect. The sign of this cor- 

 rection term shows that a real gas will effuse more rapidly or 

 more slowly than an ideal gas of equal density and specific 

 heat ratio, according as K is positive or negative. The sugges- 

 tion is made that possibly the anomalous results obtained with> 

 carbon dioxide and helium may be thus explained. The devia- 

 tions of the observed results from the results calculated for an . 

 ideal gas are, in the case of carbon dioxide, in qualitative, 

 agreement with the theory proposed. In the case of helium, 

 they would be so if that gas possesses a negative K. — Lord 

 Rayleigh congratulated the author, and pointed out that in the 

 case of very small apertures the gas laws might not be obeyed. 

 The ratio of the dimensions of the aperture to the length of the 

 mean free path determined this, and not the ratio of aperture to 

 molecular dimensions. — Prof. Ramsay and Prof. Everett ex- 

 pressed their interest in the work. — Dr. Donnan thanked Lord 

 Rayleigh for his correction, and stated that the apertures used 

 were about 3^ mm, in diameter. —Mr. E. C. C. Baly 

 read a paper on the distillation of liquid air and 

 the composition of the gaseous and liquid phases. 

 From the experiments described in this paper, the 

 author has drawn curves showing the relation between the 

 composition of the gas evolved by boiling liquid air and lO' 

 temperature, and between the composition of the liquid and ir:e 

 temperature, both at constant (atmospheric) pressure. These 

 curves enable the temperature of boiling liquid air to be at once 

 accurately determined by means of an analysis either of the 

 liquid or of the gas evolved. The measurements of temperature 



