46 



SCIENCE. 



[N. S. Vol. III. No. 54. 



some position as at A' C. If, for example, 

 strontium is introduced into the flame the 

 observer will see a red triangle appear 

 under the scale A'- C at some su.ch place as 

 D", Figs. 2 and 3. If thallium is xised 

 a green triangle will appear as at !>'". In 

 other words one can read the positions of 

 the points of the colored triangles at the 

 bottom of the scale, just as the positions of 

 the colored lines are read on the scale in an 

 ordinary spectroscope. A little practice 

 and care will enable one to read the posi- 

 tions of the triangles to 0.1 mm, and thus 

 to obtain about as good results as with the 

 customary more elaborate C-^d more expen- 

 sive form. This little piece of apparatus 

 has proved a great help in making the 

 principles of the spectroscope thoroughly 

 clear to students doing laboratory work. 

 Of course it is desirable to have a black 

 screen to prevent light from entering the 



eye from the direction of A' C. In fact it 

 is very convenient to blacken the wall for 

 a considerable space behind this apparatus. 

 Columbia College, December 10, 1895. 



THE GEOLOGICAL SOCIETY OF AMERICA. 

 The Geological Society of America held 

 its eighth annual meeting in the main 

 building of the University of Pennsylvania, 

 at Philadelphia, December 26, 27 and 28. 

 The first session of the Council took place 

 at the Hotel Lafayette at eleven o'clock on 

 the 26th. The ballot for officers was can- 

 vassed with the following result : 



President, Joseph Le Conte, Berkeley, 

 Cal.; First Vice-President, Charles H. 

 Hitchcock, Hanover, N". H.; Second Vice- 

 President, Edward Orton, Columbus, 0.: 

 Secretary, H. L. Faircliild, Rochester, N. 

 Y.; Treasurer, I. C. White, Morgantown, 

 W. Va.; Editor, J. Stanley-Brown, Wash- 



