7 
19. New form of BOLOMETER, especially designed for use with 
the above differential galvanometer. The bolometer is to 
measure very feeble radiant energy (heat). Made by J. 
Grunow. 
20. LOCAL VARIOMETER, for studying the variations of the 
horizontal component of the earth’s magnetism. Designed by 
H. Cushman and made in th elaboratory of Columbia College. 
21. KOHLRAUSCH BI-FILAR MAGNETOMETER, for measuring 
the horizontal intensity of the earth’s magnetism, its varia- 
tions, and of magnetic moments. 
22. CUSHMAN SPLIT-PLUG POTENTIOMETER. 
23. ROOD CIRCULAR WHEATSTONE-BRIDGE, with micrometer 
reading. 
24. Standard LATIMER-CLARKE CELLS AND HIGH RESIST- 
ANCES, made in the laboratory of Columbia College, by H. 
C. Parker. 
25. SPECIAL APPARATUS FOR THE DETERMINATION OF 
MOLECULAR WEIGHTS by the boiling-point method. Two 
forms. 
26. SPECIAL APPARATUS FOR THE DETERMINATION OF 
MOLECULAR WEIGHTS by the freezing-point method. This 
and No. 25 were recently presented to Columbia College by 
President Low. 
27. SMALL DIVIDING ENGINE. Made by J. Grunow. 
28. Set of seven STANDARD DISscs, used in definition of colors. 
Upon each is given the wave-length of the particular color in 
microns. A micron is equal to one-thousandth of a milli- 
meter. 
Nos. 13-28 inclusive exhibited by the Physical Department 
of Columbia College. 
29. ENGLISH DEEP-SEA AND MINE THERMOMETER in copper 
case and hermetically sealed in a tube to protect it from the 
pressure of the overlying water. Used in the mine work of 
Prof. Hallock, at Wheeling, W. Va. 
