November 20, 1885.] 



SGIEN'CE. 



443 



as the Royal society started with a close affiliation 

 to Oxford, then became, as regards its officers, for 

 many years a London society, it now returns 

 from London to one of the older universities for 

 its officers. If Professor Stokes be made president 

 (an honor which is certainly due him), the presi- 

 dent and one of the two secretaries will be Cam- 

 bridge men. This is an interesting example of the 

 fact that the older Enghsh universities, now that 

 they have been legally set free from ecclesiastical 

 control, are coming to the front in scientific re- 

 search. It gives point to the agitation now in prog- 

 ress in London for a 'teaching' university, and 

 shows, that, once ecclesiastical fetters are removed, 

 even the most ancient educational endowments 

 can produce national leaders in the physical and 

 biological sciences. 



THE NOVEMBER MEETING OF THE NA- 

 TIONAL ACADEMY OF SCIENCES. 



The meeting of the National academy of sciences, 

 held this autumn in Albany, though even smaller 

 than usual at this season, was interesting and suc- 

 cessful. The meeting began on Nov. 10, and 

 lasted four days. Only 18 of the 97 members 

 were present, and 22 papers were read, 16 of them 

 by members of the academy. The papers ehcited 

 an unusual amount of interesting discussion, and 

 the sessions, held in the new and cheery assembly 

 parlor at the capitol, were largely attended by the 

 citizens, who, indeed, did every thing to make the 

 meeting of the academy a pleasant one, with din- 

 ners and evening receptions. The local scientific 

 institutions combined to receive the academy on 

 the first evening, and the assemblage at Geological 

 haU was a large and distinguished one. 



Although the papers were divided almost equally 

 between the physical and natural sciences, those 

 in the former department were, generally speak- 

 ing, both more important and of wider interest. 

 They were almost exclusively astronomical; and 

 prominent among them, as opening new fields of 

 research, were the papers of Professors E. C. Pick- 

 ering and S. P. Langley. 



The former prep^nted to the academy the results 

 of researches hf> had undertaken in stellar photog- 

 raphy in connection with his brother, Mr. W. H. 

 Pickering, aided by a grant from the Bache fund 

 of the academy. He clearly proved that owing to 

 the recent improvements in photographic methods, 

 and particularly by the advances in dry-plate 

 manufacture, we had now a new tool in astronomy 

 of the utmost importance. The first stellar photo- 

 graphs ever taken were those of a Lyrae by the 

 elder Bond, at the Harvard observatory, in 1850. 



In 1857 his son carried similar investigations much 

 further. At first, however, they had been unable 

 to obtain clear images of stars of the second 

 magnitude, while now it was possible to print 

 those of the fourteenth, or, in other words, to trans- 

 fer to paper an image produced by an object only 

 a hundred-thousandth part as bright as formerly. 

 Professor Pickering's researches were carried on 

 by means of a new instrument he had devised and 

 constructed from the Bache fund, in which a 

 photographic lens of eight inches aperture and 

 forty-four inches focus is mounted equatoriaUy, 

 and moved by clock-work. By disconnecting the 

 clock-work, photographs of several different re- 

 gions may be taken upon the same plate, and the 

 stars distinguished by varying the exposures. 



Three different fields of investigation were here 

 opened, each of which had been traced somewhat 

 by way of exploration. One was a map of the 

 heavens ; a second, the study of atmospheric 

 absorption ; and the third, the study of steUar 

 spectra, which, by these methods, may now be 

 pursued with comparative ease. It was found 

 that the negatives would show the fines of stars of 

 the eighth magnitude perfectly, and that these 

 spectra would even bear enlargement upon paper 

 with clear definition. As the only Kmit of the 

 further extension of stellar photography is the 

 sensitiveness of the dry plate, and as this hmit is 

 plainly not yet reached, even better results may be 

 expected. 



Many photographs were exhibited, and great 

 interest was manifested in this new departure, as 

 well as in the simple, effective, and time-saving 

 devices of the author for direct comparison on the 

 same plate of a large number of objects for photo- 

 metric purposes. 



Professor Langley's paper related to 'obscure 

 heat,' and continued, as was expected, his remark- 

 able researches with the bolometer, by which he 

 has so greatly extended our notions of the invisible 

 spectrum. This time he dealt with the lunar 

 spectrum, and estimated the heat derived from the 

 uniUumined moon. Posse had estimated the tem- 

 perature of the moon's surf ace as from 200 to 500' F. 

 By studying the moon at its full with a rock-salt 

 prism obtained only after repeated faUiu'es, and 

 which, from its nature, had already required re- 

 pohshing seven times, each time necessitating a 

 new determination of its constants, he had suc- 

 ceeded on repeated occasions in securmg a spec- 

 trum which showed two curves, — one according 

 with that previously obtained in the infra red re- 

 gion beyond the visible portion of the solar spec- 

 trum, and clearly due to reflection ; and another, 

 lying entirely beyond that, as clearly due to the 

 moon itself, and revealing its real temperature. 



