362 proceedings: biological society 



d, between successive layers of atoms parallel with the crystal face, 

 the rays are reflected at maximal intensity at the angle, 5, as defined 

 by the equation n\ = 2d sin5, in which n is a whole number indicating 

 the order of the spectrum obtained. By thus measuring the distribu- 

 tion and relative intensities of the different order spectra, it is possible 

 to determine the relative atomic spacing and the atomic density of the 

 different planes of the crystal space lattice. Models showing the dis- 

 tribution of the atoms in isometric crystals, such as halite, sylvite, 

 fluorite, diamond, zinc-blende, and pyrite were presented; also draw- 

 ings illustrating the relations in calcite and dolomite. 



Mr. Swann remarked on the regularity of crystals used as gratings 

 and asked whether measurements made before and after magnetiza- 

 tion in substances capable of magnetization to saturation would show 

 different alignment through magnetization of the atoms. Mr. Wright 

 stated that experiments along that line of investigation were proposed. 



Informal communications. Mr. E. F. Mueller exhibited a fused- 

 silicate tube with a transparent quartz window made by the Thermal 

 Syndicate to replace glass and the more expensive quartz tubes used 

 in the sulphur-boiling apparatus. The new type of tube is very satis- 

 factory. 



Mr. E. G. Fischer then exhibited a new signal light designed for 

 use in the triangulation operations of the United States Coast and 

 Geodetic Survey. The oxyacetylene lamp heretofore used is costly 

 and expensive to use because of the bulkiness of the apparatus. The 

 new lamp consists of a tungsten lamp so made and mounted that the 

 filament is practically at the focal point of the parabolic reflecting 

 mirror; it is operated by dry cells. The Bureau of Standards after 

 test reported that the new lamp gives for 2 volts at 2 amperes 250,000 

 candle power in the beam at 100 feet while the old style of lamp gave 

 only 1500 candle power in the beam at the same distance. It will be 

 possible to make observations by the use of the new light on 20 to 30 

 per cent of the nights now lost in triangulation work. The relative 

 powers of the two lights were effectively demonstrated by throwing 

 the beam from each on the lantern screen. Mr. Bowie congratulated 

 the designer upon the development of the new signal. 



J. A. Fleming, Secretary. 



THE BIOLOGICAL SOCIETY OF WASHINGTON 



The 555th regular meeting of the Biological Society of Washington 

 was held in the Assembly Hall of the Cosmos Club Saturday, April 22, 

 1916; called to order by President Hay at 8.00 p.m. with 24 persons 

 present. 



On recommendation of the Council George H. Clements, Wash- 

 ington, D. C. was elected to membership. 



On recommendation of the Council the following resolutions were 

 read: 



