370 CROSS 



206. Ancel. St. John. For the purcliase of refrigerat- 



ing machine for research on crystal structure by 

 X-rays .' • $500 



207. In aid of PubUcation of Marie's Annual Inter- 



national Tables of Constants, through Theodore 



W. Richards. (Additional to 167.) .... 250 



1918. 208. Floyd K. Richtmyer. Optical properties of thin 



fiims. (Additional to 196.) 500 



209. Arthur L. Foley. Photography of phases of 



electric discharge 150 



210. Orin Tugman. Conductivity of thin metallic 



films when exposed to ultra-Aiolet light . . . 100 



211. Roswell C. Gibbs. Absorption of organic and 



silver solutions for ultra-violet and infra-red 



rays. (Additional to 203.) 250 



212. Louis T. E. Thompson. Development of a gun- 



sight for anti-aircraft guns 250 



1919. 213. Harrison M. Randall. Infra-red spectrum. (Ad- 



ditional to 188.) 200 



214. Alpheus W. Smith. Hall effect and allied phe- 



nomena in rare metals and their alloys. (Addi- 

 tional to 172.) 100 



215. In aid of publication of Marie's Annual Interna- 



tional Tables of Constants, through Julius Stieg- 



litz. (Additional to 207.) 250 



216. Arthur G. Webster. Researches on pyrodynamics 



and practical interior ballistics 500 



217. Percy W. Bridgman. Effect of temperature and 



pressure on physical properties of materials, 

 particularly thermal conductivity. (Addi- 

 tional to 185.) . . . 400 



218. Horace L. Howes. Effect of temperature on 



luminescence and selective radiation of rare 

 earths 500 



219. Frances G. ^Yick. Phosphorescence of hexag- 



onite and fluorite, at ordinary and low tempera- 

 tures ^ 300 



220. Robert W. Wood. Optical researches. (Addi- 



tional to 158.) 350 



221. Frederick G. Keyes. Heats of neutralization at 



different temperatures. (Additional to 166.) . 300 



