IG 
DEPARTMENT OF ELECTRICITY. 
In charge of Prof. F. B. Crocker. 
30. Two MACHINES for producing alternating currents of various 
frequencies, for multiplex telegraphy and other purposes. 
31. ELECTROMETER for measuring low-voltage alternating cur- 
rents. 
32. MULTICELLULAR ELECTROSTATIC VOLTMETER. 
33. SPEED INDICATOR operating by sound resonance. 
34. AIR-CONDENSERS. 
35. UNIPOLAR Dynamo. A new type now being developed. 
Nos. 30-35 exhibited by Prof. M. I. Pupin. 
36. MODEL showing construction of latest type of armature for 
dynamos and motors. 
37. COMMUTATORS OF ELECTRIC Motors, showing peculiar 
effect of wear. 
38. STANDARD INTERNATIONAL OHM recently legalized in the 
United States and other countries. 
39. WATT METER for measuring the power of alternating and 
direct currents. 
40. ELECTRO-DYNAMOMETERS for measuring alternating and 
direct currents. 
Nos. 36-40 exhibited by Prof. F. B. Crocker. 
41. THE MANUFACTURE and application of disinfectants pro- 
duced by electrolysis of salt water. Exhibited by A. E. 
Woolf. 
42. CALCIUM CARBIDE, made in electric furnace and used to pro- 
duce acetylene gas for illumination. Exhibited by E. N. 
Dickerson. 
43. APPARATUS for determining permeability of iron and steel. 
Exhibited by Max Osterberg. 
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