Humboldt State University
Robert A. Paselk Scientific Instrument Museum
Slide Wire Rheostat
W.M. Welch Scientific Company
Humboldt S-T-C; c.1930
Rheostats are used to adjust the voltage and current flow through electrical circuits. Thus, for example, if a voltage source is connected across the two terminals of the resistance coil, the central slider can be adjusted to give any voltage between the extremes. The heavy wire in this example enables it to carry a fairly high current.
The rheostat is as described in the catalog description The instrument is stamped "6 OHM" and "7.3 AMP" on the top of the bakelite slider knob, corresponding to item A in the catalog description. The left rear leg is broken off.