DEPARTMENT OF PHY SIES:. 
In charge of Prof. Alfred M. Mayer. 
1. DIVIDED CIRCLE, and mechanism giving the angle of refrac- 
tion for any angle of incidence. 
2. DIVIDED CIRCLE, and mechanism giving the angle of refrac- 
tion for any angle of incidence, and showing the directions of 
the incident and refracted rays. 
3. A series of CHLADNI FIGURES preserved in sand by Prof. 
Mayer’s process. Illustrating the vibrations of plates, and the 
errors of older figures, and the coincidence between the present 
figures and Lord Rayleigh’s theoretical deductions. 
4. POLARISCOPE with special lenses, giving very large field for 
work on crystals. 
Nos. I to 4 are exhibited by Prof. A. M. Mayer. 
5. ABBE REFRACTOMETER for determining the index of refrac- 
tion and dispersion of liquids at various temperatures. 
6. KOHLRANSCH TOTALREFLECTOMETER for determining the 
index of refraction of substances by totalreflection. 
7. LARGE SPECTROSCOPE for high dispersion and large field, 
used in recent color investigations of R. Gordon and W. 
Hallock. 
8. READING TELESCOPE by Julius Grunow, with a focusing 
mechanism by separating the elements of the objective. 
Nos. 5 to 8 are exhibited by the Department of Physics of 
Columbia College. 
g. SIMPLEX SPECTROSCOPE, for simpler spectroscopic work, 
Exhibited by H. Cushman. 
10. FIVE-ARC POTENTIOMETER, for comparison of electro-motive 
forces very accurately. Exhibited by H. Cushman. 
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