Prior to the introduction and standardization of the ohm, engineers building telegraph systems had an acute need for a unit of resistance, and they devised a number of short-lived, often local, units to meet that need.
In addition the Varley unit and the Mathiessen unit (both based on an English statute mile of wire) were telegraph units.
1. British Assn. for the Advancement of Science.
Reports of the Committee on Electrical Standards appointed by the British Assn. for the Advancement of Science...With a report to the Royal Society on units of electrical resistance, by Prof. F. Jenkin....
London: E. & F. Spon, 1873.
Les Grandeurs Électriques et leurs Unités. 2nd ed. revised and augmented.
Paris: Librairie de Gauthier-Villars Éditeur, 1884.
Ernest Spon, editor.
Supplement to Spons' Dictionary of Engineering, Civil, Mechanical, Military, and Naval. Division II.
London: E. & F. N. Spon, 1880.
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