Vertical magnetic force variometer

E.R. Watts & Son.

1947

Method: Magnetics

Description

The calibration record for this instrument indicated that 1 scale division equalled 29.4 nT and that consecutive readings were repeatable to 0.1 of a division, or 2.94 nT. Temperature compensation for this instrument was adjusted to zero over a temperature range of 15 to 55 degrees C. Measurement first required precise levelling of the instrument on a tripod, unclamping the mechanism, recording the temperature and then reading the scale through a microscope. The centre value was set at 52,000 nT. Setup and measurement time was typically 1 minute for an experienced operator.

Relative measure of Vertical Component. Resolution: 2.9 nT

Serial Number: 50,275

Year of manufacture: 1947

Origin: E. R. Watts & Son. London, England

Weight: 9 kg