CENTRAL SCIENTIFIC CO., CHICAGO. TJ. S. A. 



291 



No. 1'6933. 



No. F6831. 



6980. GAS PHOTOMETER, Precision Ponn, designed for exact photometric work and arranged so 

 that it may be used with a large number of accessories, adapting it for a variety of uses. 

 The bed consists of two large brass parallel tracks, carried on supports fitted with brass lev- 

 eling screws with sockets for permanent attachment to bench. The carriages are substantially 

 made with rack and pinion for vertical adjustment with clamping collar to. prevent slipping. 

 A pointer extending down to the track indicates the exact location of the center. Clamps are 

 furnished to hold the carriages at any desired point. The observing carriage is provided with 

 a slow motion screw for careful horizontal adjustment. The carriages are constructed to take 

 accessories with a 19 mm rod. Length of graduated portion of track, 300 cm, graduated in 1 

 mm divisions. Complete as described with two end carriages, observing carriage, platform 

 for standard lamp, and Lummer-Brodhun photometer box with collar to fit observing carriage; 

 without standard lamp or gas burner. (For illustration see preceding page.) $391.00 



Parts and Accessories for No. 6980. 



F6923. BED, 3 meters between lights, graduated in millimeters 90.00 



F6924. END CARRIAGE, for Standard or Unknown illuminant 50.00 



F6925. OBSERVING CARRIAGE, for comparison screen 60.00 



F6926. SOCKET, with cord and plug, for incandescent lamp, with 19 mm rod 3.50 



F6927. PLATFORM, for standard lamp, with 19 mm rod 6.00 



F6928. GRADUATED DISC, to be used on end carriage with incandescent lamp to secure mean horizontal 



power of lamp 10.00 



F6931. COLLAR, for use on Nos. F6924-5 when it is desired to use an accessory having a rod 10 mm in 



diameter 2.00 



F6933. UNIVERSAL COMPOUND ROTATOR, for obtaining mean spherical candle power of an incan- 

 descent lamp. It consists of a heavy frame that can be clamped to the photometer track. The 

 lamp socket is attached to a shaft mounted on ball bearings. This shaft may be adjusted in 

 a vertical plane by angles of 5. It is held to the desired angle by a pin fitting into a slot in 

 the periphery of an accurately graduated disc. The horizontal position of the lamp is read on 

 another graduated circle. The rotator is provided with two sets of brushes, one for delivering 

 the lighting current to the lamp, the other for leads to the electrical measuring instruments. 

 The rotator is also provided with all necessary pulleys and belt and may be driven by any 1/12 



H. P. motor , 125.00 



F6805. GAS BURNER, with 6-foot tip, mounted on rod to fit No. F179A Clamp 1.00 



F6807. GAS BURNER, Welsbach, complete, mounted on rod to fit No. F179A Clamp 2.50 



For COLLAR for use with Nos. F6805-7, see No. F6931. 



F6831. LAMP, Harcourt Pentane, adopted as standard by the Metropolitan Gas Referees of London 

 and used widely in this country. Recommended by the United States Bureau of Standards 

 as the flame standard for photometric work. Manufacturer's rating, 9.98 candles. Mounted 

 on adjustable support, with directions for use 110.00 



