Humboldt State University
Robert A. Paselk Scientific Instrument Museum
Portable Pointer Type Galvanometer
Leeds & Northrup Co.
Humboldt S-T-C?; before 1934?
The pointer galvanometer is a sensitive instrument for measuring current. It consists of a magnet coil with an attached needle suspended between the poles of a magnet. When an electric current is introduced into the magnet coil it induces a magnetic field, causing the coil to rotate in proportion to the current. The example here is a null instrument, that is it is designed to be used in circuits where two currents are balanced against each other, i.e. with a Potentiometer or a Wheatstone Bridge, until the meter reads zero.
The instrument is housed in a 4 1/2 x 2 3/4 x 2 3/4 in Bakelite case with LEEDS & NORTHRUP CO. / PHILADEPHIA / MADE IN U. S. A. in raised letters within a rectangular depression on the case front. The meter display is in a 2 1/2 x 1 3/4 x 1 inch high wedge shape steel container mounted on top of the case. A 1/2 x 1 1/4 inch window in front exposes the -10-0-+10 graduated scale and pointer. Two brass binding posts are placed on the opposite top rear corners of the case.