November 18, 1921] 



SCIENCE 



501 



posit of alloys of lead and tin can be obtained from 

 fluoborate solutions than is possible when deposit- 

 ing either of the metals under similar conditions is 

 established. 



The structure and properties of alternately elec- 

 tro-deposited metals: Wm. Blum. If during the 

 deposition of copper thin layers of nickel are inter- 

 posed, a deposit of greater tensile strength than 

 pure copper results due to the restraining influence 

 nickel has on the growth of copper crystals. 



In all the meeting proved to be most profitable, 

 social and instructive. 



A. D. Spillman, 



Seoretary 



THE OPTICAL SOCIETY OF AMERICA 



HELMHOIiTZ MEMORIAL MEETING 



The sixth meeting of the Optical Society 

 of America was held in Rochester, N. Y., 

 October 24, 25, 26, 1921. 113 persons were 

 registered in attendance. The attendance at 

 various sessions varied from about 35 to 100 

 or more. 



The most notable feature of the meeting 

 was the Helmholtz Memorial Meeting held 

 on the afternoon and evening of Monday, 

 October 24. The following former students 

 of Helmholtz were present: Professor Henry 

 Crew, Professor C. R. Mann, Professor Ern- 

 est Merritt, Professor E. L. Nichols, Profes- 

 sor M. I. Pupin, Dr. Ludwik Silberstein. 

 The afternoon program was as follows: 



A irief survey of the historical development of 

 optical science : Propessob J. P. C. Sodthall. 



Helmholtz' s early worlc in physics — the conserva- 

 tion of energy : Professor Henry Crew. 



Selmholtz's contributions to physiological optics: 

 L. T. Troland. 



Professor Crew exhibited lantern slides 

 showing Helmholtz at the time he wrote the 

 essay on the Conservation of Energy (age 

 26) and also at later periods of his life. 



At the evening session Professor M. I. 

 Pupin spoke informally and in most interest- 

 ing and delightful manner on his Personal 

 Recollections of Helmholtz. Professor E. L. 

 Nichols, Professor Ernest Merritt, Dr. Lud- 

 wik Silberstein, Mrs. Christine Ladd-Frank- 

 lin and Professor 0. R. Mann also spoke of 

 their memories of Helmholtz as a teacher. 



Professor Mann showed a lantern slide of a 

 photograph which he himself made on July 

 7, 1894, showing Helmholtz at his lecture 

 desk only a few days before his last illness. 



The Helmholtz Memorial addresses will be 

 published in the Journal of the Optical 

 Society of America. 



Various scientific societies were represented 

 at the meeting by delegates as follows: 



American Mathematical Society: Professor A. S. 



Gale. 

 American Physical Society : Professor M. I. Pupin, 



Dr. L. T. Troland, Professor Henry Crew. 

 American Association for the Advancement of 



Science : Professor M. I. Pupin. 

 New Yorlc Academy of Science: Professor M. I. 



Pupin. 

 American Academy of Ophthalmology and Oto- 



Laryngology : Dr. E. S. Lamb. 

 American Medical Association, Section of Ophthal- 

 mology : Dr. W. B. Lancaster. 

 American Ophthalmological Society: Dr. Lucien 



Howe, Dr. George S. Crampton. 

 Society of Illuminating Engineers: Dr. George S. 



Crampton. 

 American Psychological Association: Dr. L. T. 



Troland, Mr. Prentice Reeves, Professor C. E. 



Perree, Dr. P. W. Cobb. 



The following papers were presented at the 

 regular sessions of the Society on October 

 25 and 26. 



Photo-electric potentials from the retina: E. L. 

 Chaffee and W. T. Bovie (to be published in 

 full in the Jour. Op. Soc. Am.). 



Intensity and composition of light and size of 

 visual angle in relation to important ocular func- 

 tions: C. E. Perree and Gertrude Eand. 



A theory of intermittent vision: Herbert E. Ives 

 (to be published in full in the Phil. Mag.). 



An analysis of the visibility curve in terms of the 

 Weber-Fechner law and the least perceptible 

 brightness: Enoch Karrer (to be published in 

 full in the Jour. Op. Soc. Am.). 



A quantitative determination of the inherent satur- 

 ation of spectral colors: L. T. Troland (to b« 

 published in full in the Jour. Op. Soc. Am.). 



The interrelations of brilliance and chroma studied 

 by a flicker technique : L. T. Troland and C. H. 

 Langford (to be published in full in the Jour. 

 Op. Soc. Am.). 



A proposed standard method of colorimetry : Her- 



