730 



OPTIC PROJECTION 



Ultra-violet, quartz optical sys- 

 tem for 641-642 



radiation 567, 641-642 



projection of 640- 642 



United States Geological Survey 147 

 Units of alternating current . 484-486 



Units of direct current 475-483 



Units of electricity. . 475, 484 



University of Pennsylvania and 



animal movement 682 



Unpacking moving picture ma- 

 chine 401 



Uranium arc for spectra 628 



when in the positive, and 

 when in the negative elec- 

 trode 640 



Valspar varnish for water cells 



205, 264 



Varnishing lantern slides 205 



Vertical microscope for high 



powers 283 



Vertical knife switch 516 



Vertical projection 33 



Violet lines in arc stream 546 



Visibility of objects 227 



Vision, daylight and twilight 



121, 175, 444 

 Vision, experiments with normal 



651-659 



defective 659-672 



persistence of in moving pic- 

 tures 



Visual angle 228 



Voigtlander und Sohn 226, 250 



Volt and voltage 476, 484 



Voltage, alternating current .... 484 



by Ohm's law 521 



intermediate 544 



of line and arc 544 



of line, voltmeter connections 475 



not present in the line 46 



Voltmeter, connection for arc 



voltage 476 



connection to circuit 478 



direct current 478 



for line voltage 475 



for polarity testing 508 



soft cored 510 



Walgensten. 3, 675-677 



Wall diagrams 329, 355 



Wall receptacle 86, 503 



Water-cell, 13, 15, 18, 57, 63, 71, 161, 

 194, 222-223, 237, 239-240, 

 264-266, 276-277, 281-282, 

 287, 299, 301, 309, 355, 365, 

 421, 432, 571, 592, 604-609 

 absorption of radiant heat not 

 affected by temperature . . . 606 



effect of alum, etc. in 607 



efficiency 568-569 



light and energy absorbed by 



604-607 



in micro-projection 237 



the microscope stage in 608 



how to make 264 



need in moving pictures . .421, 432 

 with ordinary microscope. . . 266 

 position in micro-projec- 

 tion 239, 240 



shadow from 57 



stage 239-240 



sunlight 161 



sun and micro-projection .... 287 

 with two-lens condenser. . 365, 421 



Water cooled rheostat 527 



Waterhouse, Gen. J 673 



Watt, and wattmeter. 477, 482-483 



Watts, alternating current 485 



equal volts times amperes 



477, 521 



Wattmeter 482-483 



amperage by 483 



connecting 482 



power at arc by 482 



power from dynamo 483 



White, Dr. A. C 673 



White-washed wall screen 455 



Wiedemann's Annalen 647 



Williams, Brown & Earle 



59, 91, 107, 130, 131, 182, 183, 300 



Wimmer 9, 202 



Winding and rewinding moving 



picture film 430 



Widow in lamp -house 



72, 267, 402-403 

 Window shades for darkening 



the room 445-447 



Wires for the electric circuit . 496-505 



how to connect 503 



insulation of 497-498 



wrong polarity 51, 506-511 



Wiring the arc lamp, 10, 13, 15, 71, 

 84, 263, 324, 339-340. 399, 496- 

 535, 639 



