The Rawson Electrical Instrument Company of Cambridge, Massachusetts, was a respected manufacturer of precision electrical measuring devices during the early to mid-20th century. Their electrostatic voltmeters were particularly valued for their ability to measure very high voltages with minimal loading effects on the circuit being tested. These instruments were essential tools in early power distribution and high-voltage research laboratories.
Electrostatic meters operate on the principle of attraction and repulsion between charged plates, allowing them to measure both AC and DC voltages. The inclusion of a 'clamp' mechanism allowed technicians to hold a reading in place for easier recording. These devices represent a transition period in electrical engineering before the widespread adoption of electronic multipliers and digital meters.
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