Jantjaet 20, 1911] 



SCIENCE 



113 



/ 



" Expectorants," by V. E. Henderson and A. H. 

 Taylor. 



SPECIAL ARTICLES 



ELLIPTIC INTERFERENCE IN CONNECTION WITH 

 REFLECTING GRATING 



In my earlier papers^ and in a forthcoming 

 theoretical account of the subject, I have 

 shown the practical advantages obtained by 

 associating the interferences of thin plates 

 with the diffractions of the transparent 

 grating — a subject originally suggested to me 

 by the phenomenon of coronas, in which a 

 marked interference phenomenon was also 

 superposed on the diffractions. These elliptic 

 fringes may, however, be evoked in other ways 

 than those discussed, and it is to some of these 

 that I venture to refer here. 



Let the oblique mirror in Michelson's appa- 

 ratus, for instance, be the usual plate of glass 

 and replace the two opaque mirrors M and N 

 by identical small reflecting gratings, set at 

 the angle of diffraction of the spectrum, 

 symmetrically to the incident rays. Here the 

 elliptic interferences will be seen in the tele- 

 scope at right angles to the rays issuing from 

 the collimator. This adjustment is virtually 

 the same as the plan of returning the dif- 

 fracted spectra normally to the oblique trans- 

 parent grating, discussed in the preceding 

 paper in this Journal. The fringes are rings. 



Again, in a simple spectrometer adjustment 

 for grating spectra, suppose the grating (either 

 transmitting or reflecting) to be separated 

 into two halves by a division parallel to the 

 ruling. Then on displacing one of the halves, 

 micrometrically, parallel to itself from its 

 original coplanar position, elliptic interference 

 must show itself in a way which is perhaps 

 more direct than any of the methods hitherto 

 treated. The fringes are straight. 



Cakl Barus 



Beown Univebsity, E. I. 



THE AMERICAN SOCIETY OF NATURALISTS 

 The twenty-eightli annual meeting of the Amer- 

 ican Society of Naturalists was held in the 

 auditorium of the New York State College of 

 Agriculture at Cornell University on December 

 'Science, XXXII., 1910, p. 92; Am. Journal of 

 Science, XXX., 1910, p. 161. 



29 and 30. The eastern branch of the American 

 Society of Zoologists so arranged its program 

 that members were enabled to attend the Nat- 

 uralists' meeting. Many of the members of the 

 Association of Anatomists and American Society 

 of Bacteriologists which were meeting in Ithaca 

 also attended the program. Although the Bot- 

 anical Society of America met elsewhere a number 

 of botanists came instead to the meetings of the 

 Naturalists. It may fairly be said, judging from 

 the number present at both sessions, that the 

 Naturalists' symposium was the chief feature of 

 general interest at the entire Ithaca meetings. 



The one cause of general regret was the un- 

 avoidable absence of the president. Dr. D. T. 

 MacDougal, who was ill in the Johns Hopkins 

 Hospital. President MacDougal had so carefully 

 planned the program and had done so much to 

 instill enthusiasm into the entire arrangements 

 that all felt the pronounced success of the occa- 

 sion to be the result of his efforts. 



Dr. MacDougal's well-thought-out and richly 

 suggestive address on " Organic Response " was 

 read at the annual dinner of the society by the 

 vice-president, Professor H. S. Jennings. 



At the meeting of the executive committee and 

 at the business session of the society there was a 

 general expression of the feeling that the present 

 affiliation of the biological societies was highly 

 desirable. The Anatomists, Bacteriologists, Zool- 

 ogists and Naturalists which met at Ithaca might 

 meet comfortably at many of the universities of 

 the country which are situated, as Cornell is, in 

 a small town. It was also felt that there was a 

 far more favorable opportunity for personal dis- 

 cussions and exchange of ideas at a smaller meet- 

 ing than at a more general one. 



The Anatomists, Zoologists and Naturalists had 

 a joint smoker at the Ithaca Hotel on Wednesday 

 evening. 



The Naturalists' dinner was given on the fol- 

 lowing evening at the Ithaca Hotel and was well 

 attended. After the dinner the president's ad- 

 dress was read. 



The scientific program was given on Thursday 

 afternoon and on Friday both fore- and afternoon. 

 The central topic of the discussions was the 

 pure line conception in the study of inheritance 

 and evolution. Most of the papers in the first 

 part of the program seemed to support the views 

 of Professor Johannsen, while several of the later 

 papers on the program seemed to strongly suggest 

 that selection and a modified Lamarckian view 

 were yet to account for important factors in the 



