640 



SCIENCE 



[Vol. I.VI, No. 1457 



Adjustable sensibility saecliarimeter (made by 



J. & J. Fric). 

 22. Bureau or Standards (Optical Instruments 



Section) 

 A variable power magnifyiiig stereoscope. 



23. Christine Ladd-Franklin 

 Charts illustrating the Ladd-Franklin theory of 

 color vision. 

 5. Bureau of Standards Laboratory Exhibits 

 On account of the limited space in the exhi- 

 bition room and the inconvenience of disturb- 

 ing complicated "built-in" apparatus the 

 Bureau of Standards contributed very little to 

 the exhibits in the exhibition room. The 

 bureau apparatus was, however, open to inspec- 

 tion in the rooms where it is regularly used. 

 Instruments . and apparatus thought to be of 

 most interest to the Optical Society were listed 

 and described in the advance program, which 

 thus served as a guide to visitors. This list is 

 given below. 

 Standard horizontal photometers (in charge of 



B. S. Willis). 

 Flicker photometers and colored test solutions, 

 for photometric observers (in charge of B. S. 

 Willis). 

 Photometric distribution apparatus (in charge of 



B. S. Willis). 

 Integrating photometric sphere and Taylor re- 



flectometer (in charge of B. S. Willis). 

 Koenig-Martens Spectrophotometer (in charge of 



M. Katherine Frehafer). 

 Photoelectric spectroradiometer (in charge of 



K. S. Gibson). 

 Hilger sector photometer with quartz spectro- 

 graph for ultra-violet spectroradiometry (in 

 charge of H. J. McNicholas). 

 Spectrophotometer (color analyzer) for measuring 

 spectral reflection (designed by Keuffel & 

 Esser and the Bureau of Standards) (in charge 

 of E. E. Lofton). 

 Exponential spectrophotometer for liquids (in 



charge of Irwin G. Priest). 

 Micrometer-microphotometer for measuring rela- 

 tive wave-lengths and photographic densities in 

 spectra (in charge of W. F. Meggers). 

 Commercial (life-test) photometric equipment (in 



charge of Miss R. M. Collins). 

 Photometer for measurement of brightness of 

 self-luminous materials (in charge of W. H. 

 Wadleigh). 

 Apparatus for the determination of hue sensi- 

 bility (wave length differences perceptible by 



difference in hue) and the visibility of radiant 

 energy (in charge of Irwin G. Priest). 



Eotatory dispersion eolorimetric photometer (in 

 charge of Irwin G. Priest). 



Standard rotatory dispersion apparatus for the 

 determination of the normal stimulus of gray 

 (in charge of Irwin G. Priest). 



Special apparatus for the determination of the 

 normal stimulus of gray with full field illumina- 

 tion (in charge of Irwin G. Priest). 



Fizeau expansion apparatus (in charge of C. G. 

 Peters). 



Dimensional change apparatus (in charge of 

 C. G. Peters). 



Scale ruling machine (in charge of C. G. Peters). 



Portable gas interferometer, laboratory gas inter- 

 ferometers (in charge of E. E. Weaver). 



Disappearing filament optical pyrometer (in 

 charge of C. 0. Pairehild). 



Universal polarimeter (in charge of A. Q. Tool). 



Crystal growing apparatus and various crystals 

 (in charge of F. P. Phelps). 



Photographic sensitometric apparatus (in charge 

 of Eaymond Davis). 



Metallographic microscopes (in charge of H. S. 

 Kawdon and S. Epstein). 



Dalby optical load extension recorder (in charge 

 of John E. Freeman, Jr.). 



Photomicrographic apparatus (in charge of E. E. 

 Lofton). 



Microprojection of stratified soap films (in 

 charge of P. V. Wells). 



Ultramicroscope (Zeiss Slit) (in charge of P. V. 

 Wells). 



General Electric oscillograph, Bureau of Stand- 

 ards modifications (in charge of E. A. Web- 

 ster). 



Cathode-ray oscillograph (Braun Tube) (in 

 charge of Miss F. Kenyon). 



Projectile camera (in charge of A. H. Selbnan). 



Optical glass plant (in charge of A. N. Finn). 



Optical shops: Highest precision hand work (in 

 charge of J. Clacey) ; Machine grinding and 

 polishing (in charge of F. C. Weaver). 



The president announced the election of Pro- 

 fessor A. A. Michelson and Dr. S. W. Stratton 

 to honorary membership in the society. 



The meeting was concluded by an informal 

 dinner at the Hotel Ebbitt. 



The nest meeting will be held at Cleveland, 

 in October, 1923. 



Irwin G. Priest, 



Washington, Secretary 



