October 23, 1885.] 



SCIENCE. 



359^ 



to determine the annual parallax of the star 40 o^ 

 Eridani. The principal star of this system has a 

 proper motion of 4'' a year ; and, at a distance of 

 82'', there is a double companion, which has the 

 same proper motion, while nearly between them 

 is a small star which does not move. Professor 

 Hall finds for the parallax of 40 Eridani 



TT = 0''.223 ± 0''.0208. 

 a result rather smaller than might have been ex- 

 pected, but one which he considers worthy of con- 

 siderable confidence. 



Comet Tuttle (1790 II.). — Swift reports having 

 found the comet on August 13. He describes it 

 as " fairly bright on a dark sky, and shows a strong 

 condensation at the centre." As far as we have 

 learned, he is the only one who has seen the comet 

 at this retm-n, except the astronomers at Nice. 



1 he nebula in Andromeda. — The new star in 

 the Andromeda nebula continues to decrease in 

 brightness. On October 10 it was estimated as 9.9 

 magnitude with the transit circle of the U. S. naval 

 observatory. This estimate depends upon the same 

 star used in the previous observations {Science vi., 

 310). 



Comet 188 1 III (&) Tebbutt.— Dr. de Ball in- 

 tends to compute the orbit of the above comet, and 

 calls for any observations still unpubhshed. Ad- 

 dress, ' Dr. de Ball, Observatoire, Ougree, Liege, 

 Belgium.' 



NOTES AND NEWS. 



The curriculum of the University of Michigan 

 has been altered and enlarged in order to pro- 

 vide a specific course of study for students who 

 wish to devote their tinae largely to biological 

 work, either as a preparation for the study of 

 medicine or with a view to teaching or engaging 

 in biological research. Zoology, botany, and phy- 

 siology^ are the most prominent subjects of the 

 course, but full opportunity is given for extended 

 work in physics, chemistry, paleontology, and 

 other sciences. 



— The first one of a course of ten lectures on 

 physiology and hygiene, under the auspices of the 

 Cincinnati society of natural history, was given on 

 October 3. These lectures are free to teachers of 

 the public schools, and the interest is shown by 

 the apphcation of about seventy-five teachers for 

 tickets to the course. This is the second course 

 given by the society, the first having been on 

 botany. 



— Cable dispatches announce the death of 

 Thomas Davidson, preeminently the British student 

 of Brachiopoda. He was born in Edinburgh, 

 May 17, 1817, and received most of his education 

 on the continent. A review of his latest work will 



be found in Science (v. , 409). The monograph of 

 recent Brachiopoda, there referred to as in jjrepara- 

 tion, has actually been completed. Under date of 

 June 1, in a letter to a friend in this country, which 

 we have been permitted to see, he says that it will 

 be accomj)anied by 30 plates, containing 865 figures, 

 and adds : " I can assure you that this work has 

 taken me a long time to complete, and, since I have 

 been ill for several months, it is fortunate that all 

 is ready to send to the printer. I have thus been 

 able to bring to successful conclusion all that I had 

 proposed to accomplish, and I am now ready to 

 leave this world as soon as God walls." This in- 

 defatigable investigator adds that he has also com- 

 pleted a bibliography of the Brachiopoda which will 

 occupy about 200 quarto pages and contain about 

 3400 titles ; the first part will be printed by the 

 Palseontographical society this year and the balance 

 in the volume for 1886. "I have been able," he 

 concludes, ''to make a very rich and nearly com- 

 plete collection of recent Brachiopoda, and I pro- 

 pose to bequeath the whole of this, as well as all 

 my fossils, to the British museum." 



— James Macfarlane, well-known for his useful 

 ' Geological railway guide ' and ' Geologist's travel- 

 ling handbook,' died suddenly on the 12th instant 

 at his home in Towanda, Penn., of heart disease. 

 He was born Sept. 2, 1819, at Gettysburg, Penn. 



— In the Philosophical magazine for August, 

 Shelf ord Bidwell, Esq. , in a paper entitled ' The 

 sensitiveness of selenium to light and the develop- 

 ment of a similar property in sulphur,' describes 

 a series of very interesting experiments, which 

 would seem to show that the action of hght in 

 varying the resistance of a selenium cell arises 

 from the fact that the conductivity of the cell is 

 due to a selenide of the metal with which it is an- 

 nealed (the crystalline selenium itself being prac- 

 tically a non-conductor), and that the formation 

 of this selenide is assisted by direct radiation of 

 Hght. With sulphur and silver he formed cells 

 showing the same variation of resistance in hght 

 and darkness, and showed very plainly that the 

 union of sulphur and silver into the sulphide, at 

 ordinary temperatures, is greatly assisted by dh'ect 

 radiation, and is not due to rise of temperature of 

 the substances themselves. The whole analogy of 

 the actions of sulphur and selenium in the two 

 cases, coupled with the enormously high resistance 

 of pure selenium when crystallized between glass 

 plates or substances with which it does not com- 

 bine, seem to render his conclusions highly prob- 

 able. The whole paper is of great mterest. 



— The Russian government has just despatched 

 one of the foremost mining authorities of the day, 

 M. Gulishambaroff, to Askabad, in Central Asia,. 



