September 12, 1895] 



NATURE 



48/ 



conditions of thunderstorms, and an investigation of the effects 

 of the earthquake at Florence on May i8 last, by C. Bassani. 



An examination of the gases liberated from certain of the 

 sulphurous waters of the Pyrenees reveals, in the hands of M. 

 Ch. Bouchard, the interesting fact that the formerly assumed 

 nitrogen (from which the Spanish physicians have named these 

 waters azoades) consists in part of free argon and helium. The 

 collected gas was in each case, after treatment with potash and 

 |)hosphoric anhydride, introduced into a Plucker tube containing 

 magnesium wire. Under the action of the silent discharge the 

 nitrogen rapidly disappeared by combination with magnesium, 

 leaving a residue exhibiting the characteristic rays of both argon 

 and helium for the gas derived from the waters of la Raillere, 

 helium from the springs of Bois, and helium together with probably 

 an unknown gas from the waters of lowest temperature at Bois. 



The use of magnesium wire and the silent discharge 

 is due to MM. L. Troost and L. Ouvrard, who show 

 that the magnesium vapour produced very rapidly combines 

 with nitrogen under the conditions obtaining in the tubes. 

 Further, the continued action of a powerful silent discharge, for 

 some hours after the spectroscopic evidence proves the absence 

 of nitrogen, results in a gradual diminution in intensity of the 

 helium and argon rays. Finally a complete vacuum is pro- 

 duced, hence it appears that magnesium combines with argon 

 and helium under these circumstances. Platinum appears to 

 behave like magnesium towards argon in PlUcker tubes with the 

 silent discharge. 



The additions to the Zoological Society's Gardens during 

 the past week include a Bonnet Monkey (Macacus sinkus, 9 ) 

 from India, presented by Mrs. Ball ; an Emu {Dromietis nova- 

 hollandiic) from .Vustralia, presented by Mr. C. W. Williams ; 

 a Raven (Cori'tis corax), British, presented by Mr. W. Weeker ; 

 a Royal Python (Python nginis) from Dahomey, West Africa, 

 presented by Mr. C. II. Harley-Moseley ; a Common Chame- 

 leon (Chaiiiecleon vulgaris) from North Africa, presented by Mr. 



C. Sampson ; a Snake (Phryiioiiax eiitropis), a Snake 



(Phrynonax fascia/us) from Trinidad, presented by Mr. R. R. 

 Mole ; a White-tailed Sea Eagle (Haliiittis alhieilla) from 

 Scotland, two Diamond Snakes {Morelia spilotes) from 

 Australia, deposited ; eight Amherst Pheasants (Thaumaka 

 amhersliii:), six Ring-necked Phea.sants (Phasianns torqiialus), 

 two Japanese Pheasants (Phasianus versicolor), a Temminck's 

 Tragopan (Ceriornis lemmiiicki), bred in the Gardens. 



OUR ASTRONOMICAL COLUMN. 



The Proper Motion of the Sun. — In the September 

 number of the Bidlelin Astroiiomii/ue M. Tisserand gives an 

 interesting account of a method of determining the proper motion 

 of the sun from stellar proper motions. Denoting by in and in' 

 the values of the annual proper motions of the stars, f the space 

 described by the sun in one year, this space being measured with 

 the same unit as the distance (p) of the sun, and .\and D the 

 Right .Vscension and Declination of the apex of the sun's way, the 

 formuke for reduction become 



III cos S = - cos Dsin (o - X) 

 P 



—!—z. = - - sin D -^ 1 cos D tan 5 . cos (a - A). 

 cos & p p 



In the second equation the second term changes its sign with 

 tan 8, p changes its value from star to star. Assuming that the 

 mean of the values of this term will be small or zero, and that 

 2 represents the arithmetical mean, we have 



\cos «/ 



Now, because sin D is positive, the mean values of the left- 

 hand side of the equation ought to be negative. If there were 

 no proper motion to the sun, they should be zero. 



I'sing the catalogue of 1054 stellar proper motions, motions 

 "f M. Stumpe (//j-/r. Nac/i., Nos. 2999-3000, year 1890), only 



"<;> 



those stars have been employed the declinations of which are 

 comprised between - 30 and + 30°, and the proper motions 

 less than o"'64. 



The mean values for the sum above were then tabulated for 

 every hour of Right .\scension. These were found to be all 

 negative, as they ought to be, and they did not differ very 

 much from one another. For 585 stars the mean value was 



- o"-i<;i. 



M. Tisserand further investigated the values obtained from 

 another catalogue of 2641 stellar proper motions, by M. Bossert, 

 in exactly the same way. Here the mean values were still found 

 all to be negative, and not verj' different from one another. 

 From 1537 proper motions the value obtained was -o"'i3l. 



By taking only the proper motions of stars comprised be- 

 tween declinations ±15°, the value obtained does not differ 

 materially from that given above. In the interval then of a cen- 

 tury, for each hour of right ascension, the declinations of all the 

 stars have diminished (in the mean) by quantities comprised 

 between 10" and 20" ; and he says, " il nous semble que cela 

 donne une preuve materielle frappante du mouvement du 

 Soleil." 



The Rot.ation of Venus. — A difficult problem in observa- 

 tional astronomy is the determination of the period of the rota- 

 tion of Venus. M. Schiaparelli, whose powers of observations 

 have been often put to the test, still thinks that the planet 

 accomplishes one rotation in the same time that it takes to travel 

 round the sun, or, in other words, the same hemisphere is always 

 turned towards the sun. M. Leo Brunner, however, who has 

 made during three months a great number of drawings, which 

 appear to corroborate his statement, seems to be of quite a dif- 

 ferent opinion, for he says: " J'ai le plaisir de vous annoncer 

 que je viens de decouvrir la vraie periode de rotation de Venus, 

 qui ne differe que de quelques minutes de celle de notre terre. 

 Cette decouverte est hors doute, car j'ai pu voir arriver et passer 

 des taches plusieurs jours avec la plus grande distinction. Nul 

 doute a cet egard." It must not be forgotten, however, that the 

 observation of \'enus is one attended by great difficulty. Even 

 Brunner's drawings and those of Schiaparelli made of the planet at 

 the same time are very different. There seems to be no doubt 

 that the observations are all verging on the limit of visibility, 

 and that the 224 days or the 24-hour period are just as probable 

 as ever. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



C.VMBRIOGE. — The following appointments have been recently 

 made by the governing bodies of the undermentioned colleges : — ■ 

 At St. John's, Mr. R.JH. Adie, a Lecturer in Natural Science ; at 

 Magdalene, Mr. G. T. .Manley, Lecturer in Mathematics ; at 

 Trinity, Mr. G. T. Walker, Lecturer in Mathematics, and 

 Messrs. W. C. D. N\'hetham and J. W. Capstick, Lecturers in 

 Natural Science ; at Emmanuel, Mr. A. Eicholz, Lecturer in 

 Natural Science : at Sidney Sussex, Mr. R. H. D. Mayall, 

 Lecturer in Mathematics ; at Selwyn, Mr. L. A. Borradaile, 

 Lecturer in Natural Science. 



NO. 1350, VOL. 52] 



According to Science, Prof. Bonnet, Professor of Anatomy 

 in the University of Giessen, has received a call to Greifswald ; 

 and Dr. M. Miyoshi has been appointed Professor of Botany in 

 the University of Tokyo. 



Mr. Chas. Berrv, horticultural lecturer to the East Suffolk 

 County Council Technical Instruction Committee, h.as been 

 appointed Instructor in Horticulture l)y the Devonshire County 

 Council, and will enter upon his duties at the end of September. 



The prospectus of Day and Evening Classes at the Battersea 

 Polytechnic Institute for the session 1895-6, has reached us, 

 and contains full information respecting the numerous classes 

 held at this well-appointed institution. Several new classes are 

 to he formed, and special provision is made for the needs of 

 students who are desirous of entering for the examination of 

 London University, from the matriculation to the final B.Sc. 



The fourth annual report (1894-5) of the Dei^artment of .-\gri- 

 culture, Vorkshire College, Leeds, has been published, and shows 

 clearly that a great deal of useful work has been carried on 

 during the past twelve months, and has, on the whole, met witti 

 very satisfactory success. With one exception (that of the 

 classes for elementary teachers) each branch has exhibited 

 much growth. The lectures given to farmers and others were 



