178 Hartmann & Braun. Bockenheim- Frankfort o. M. 



armature wire prevents the motor from consuming any current except 

 when in motion. 



95. Automatic Cut-outs for a certain maximum or minimum. 

 Efficient within 3%. 



96. Automatic voltage Regulator. The sliding contact which 

 serves for connecting and disconnecting resistances is moved by a screw 

 in a straight line. The screw is coupled to a small electro-motor. The 

 latter takes its current in either direction through a contact voltmeter. 



. 97. Automatic Switch for regulating the voltage by connecting 

 and disconnecting accumulators w : ith the circuit. Similar in construction 

 to No. 96. 



98. Differential Arc Lamps with stationary luminous point, 

 A steady uniform light is obtained by the introduction of a clock work 

 which retards the movement of the carbons. Low structure, various 

 decorative designs, to burn from 5 to 15 hours, for currents from 1 to 15 amp. 



96 and 97. 



99. Small Electromotors of Vao > Vis and Vs HP ' wound as 

 series motors, and of l /4 ,' l /2 and * HP wourid as shunt motors. 

 The speed of the former varies according to the load, the latter run at 

 almost constant velocities. Both types are very efficient and well built. 



100. Portable dynamo -machine for blasting; in wood case 

 with leather strap. It generates at a speed of about 3 rotations of the 

 crank per second 0.85 amp. and 75 volts (efficiency of 65 watts). Total 

 weight 10.5 kilos. The igniting electrodes consist of thin platinum wires 

 embedded in the cartridge. 



Portable measuring appliances for use in the installation 

 of electrical plants. 



Exhibited at the entrance of the Exhibition room. 



101. Portable Measuring Apparatus for Cable Laying. Two- 

 wheeled firmly built truck fitted with resistance bridge for usual resistances, 

 an apparatus for testing insulation resistances by the method of 

 deflection, with a telescope galvanometer. Underneath a space is 

 provided for a stand upon which the galvanometer may be placed. By 



