PL 89 Technology System of Electricity Alexander Hogg 1788
Caton's Electrometer, Henly's Quadrant, Electophorus
Antique Copper engraving engraved by Barclay, printed on hand made hemp and flax laid paper.
Published "According to an Act of Parliament" by Alexander Hogg, at the Kings Arms No 16 Paternoster Row, London circa 1788
Condition= Very Good, with complete plate mark, no tears/creases, light soiling across top of page.
Mr. Canton's Electrometer consisted of two balls of cork, or pith of elder, about the size of a small pea, suspended by fine linen threads, about 6 inches long.
Henly's Quadrant/Electrometer: Mr. Henly's quadrant electrometer, fixed upon a small stand, from which it may be occasionally separated, and fixed upon the prime Conductor
Plate mark = 23.5 x 38 cm (9.4 x 15.2 inch)