172 



Hartmann & Braun, Bockenheim- Frankfort o. M. 



Rheostats for scientific exact measurements 



very accurately calibrated, 

 of constantan or manganine wire, wound so as to obviate self-induction. 



53. Series of 0.1, 0.2, 0.3, 0.4, 1, 2, 8, 4, 10, 20 etc. to 4000 

 ohms, i. e. in combinations of upwards of 11 111.1 ohms, with plug 

 connections. Also in 



54. Decades of 4 x 2 + 1 4- 1 or 10 x [0.1, 1, 10, 100, 

 1000, 10 000, 100 000] ohms, with plug connections. Also in the form of 



55. Branching Rheostats, with pairs of 1, 10, 100, 1000 and 

 10 000 ohms. Also in the form of 



56. Resistance Bridges composed of series or decade resistance 

 boxes with branch resistances. Finally,? injthe form of 



57. Shunts and Addition Rheostats, for diminishing the sensi- 

 tiveness or extending 1 the range of galvanometers. 



Rheostats for industrial exact measurements. 



58. Single Resistances of 1, 10, 100 up to 10000 ohms. 



59. Series of 1, 2, 3, 4; 10, 20, 30, 40; 100, 200 etc.; giving a 

 total maximum of 11 110 ohms, with plug connections. Also in 



60. Decades of 10 x [1, 10, 100, 1000] ohms with crank changer. 

 Finally, in the form of 



61. Resistance Bridges, combined decade and branch resistances. 



62. Portable Resistance Bridge, with galvanometer, of 0,01 

 to 1 million ohms, for comparing E. M. F.'s of single cells, con- 

 sisting of 4 decades, 3 pairs of branch resistances, pole reverser, switch 

 and with key; all parts fitted with crank manual; in case fitted with lock. 



All resistances are joined by separate conductors to the connecting pieces, 

 there being no common conductors. By means of terminal plugs which are to 

 be inserted at the side any one of the resistances may be branched off. 



