222 



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



No. F4733. 



No. F4731. 



F4725. MEGOHM BOX, Standard, with five groups of coils of 200,000 ohms each. Six pillars, well in- 

 sulated, are used on a hard rubber top, there being 200,000 ohms between each pair of pillars. 

 There is a double contact post on top of each pillar, so that these can be connected together 

 with copper links. In finely finished hardwood box $187.50 



F4727. TENTH-MEGOHM BOX, Standard. In four units of 10,000, 20,000, 20,000 and 50,000 ohms. An 

 infinity plug separates each coil from the one next to it. Segments are insulated by hard rub- 

 ber above the hard rubber top in order to increase the insulation. In finely finished hardwoo:! 

 box 62.50 



WHEATSTONE BRIDGES AND POTENTIOMETERS 



F4731. RESISTANCE BOX and WHEATSTONE BRIDGE Combined. Polished hardwood mahogany 

 finished box with hard rubber top %-inch thick. Heavy brass blocks of new design (see No. 

 F4711) are used. For other details of construction, see page 220. The bridge coils are six in 

 number, 1, K) and 100 ohms on each side. The rheostat coils are twelve in number, viz: 1, 2, 

 3, 4, 10, 20, 30, 40, 100, 200, 300, 400 ohms. The total range of measurement is therefore from 

 0.01 to 111,000 ohms. The binding posts for battery, galvanometer, and unknown, and keys 

 with platinum contacts for battery and galvanometer are conveniently placed, and all hidden 

 connections are clearly indicated by lines on the top of the box. Guaranteed accuracy, %%. 40.00 



F4733. RESISTANCE BOX and WHEATSTONE BRIDGE Combined. An exceptionally high grade box 

 of the finest materials and first class workmanship. The blocks are of new and improved de- 

 sign (see No. F4711), and the other details of construction are as described on page 220. The 

 rheostat coils are sixteen in number, viz: 1, 2, 3, 4, 10, 20, 30, 40, 100, 200, 300, 400, 1000, 2000, 

 3000, 4000 ohms. The bridge coils are eight in number, 1, 10, 100 and 1000 ohms on each side. 

 The total range of measurement is therefore from 0.001 to 11,110,000 ohms. The binding posts 

 for battery, galvanometer, and unknown, and keys with platinum contacts for battery and 

 galvanometer are conveniently placed, and all hidden connections are clearly indicated by 

 lines on the top of the box. Has two traveling plugs. Guaranteed accuracy, 1 /io% 55-00 



F4739. BRASS PLUG, with knurled rubber top, as used on our Resistance Boxes 26 



