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



221 



NO. F4719. 



F4713. EESISTANCE BOX, same as No. F4711, but with total resistance 11,110 ohms, as follows: 1, 2, 3, 

 4, 10, 20, 30, 40, 100, 200, 300, 400, 1000, 2000, 3000 and 4000 $45.00 



F4719. RESISTANCE BOX, Dial Decade Design. A 3-dial resistance box having a total resistance of 

 1110 ( = 10x1 + 10x10+10x100) ohms, mounted in a mahogany finished hardwood box, with 

 hard rubber top about. 15x40 cm. Contact with the blocks at the end of the swinging arm is 

 made by a multiple brush with ends bent so that they are not tangent to the circle in which 

 they move and therefore do not wear rings in the blocks. The coils are of the same descrip- 

 tion as those used in our other resistance boxes (see page 220), and are guaranteed to % of 

 1% 45.00 



RESISTANCE BOXES, Dial Decade Design. High grade hard rubber top, mounted in a wood 

 case, or, if preferred, in a perforated metal case so that the coils may cool rapidly or be im- 

 mersed in oil to give extra large current carrying capacityi The dials may be rotated in either 

 direction continuously, the dial switches make thoroughly reliable contact and the brushes are 

 set so that they do not wear rings in the blocks. Guaranteed accuracy 1/10 per cent. 



No A 



No. of dials 3 



Smallest resistance, ohms 10 



Total resistance, ohms 11,100 



F4721. EESISTANCE BOXES, in wood case $80.65 



F4722. EESISTANCE BOXES, in metal case 80.65 



