$995 USD + postage included

A fine and rare 6 inch folding arm, circular protractor by William Simms c.1820


15 cm. circular




William Simms

Country of manufacture

UK and Ireland

Categories: Calculating, Drawing Instruments, Engineering antiques, Tools


A fine and rare six inch folding arm, circular protractor by William Simms PRIOR to the formation of the famous duo of Troughton & Simms c.1826. Signed SIMMS, LONDON in bold block letters and serialised * 11. Not geared as in later examples, the outer ring 360 degree, finely divided (not engine) according to Simms special method which intrigued Troughton and the scientific instrument community. Geared and locking slow motion worm and screw opposite a vernier reading from 0-25 degrees in 1/10 degree divisions. Constructed of bright and anodized brass, there is not a screw touched or out of place. Center glass has a green tint and cross hairs (etched) are intact. The 17 x 17 x 5 cm. mahogany case has both hooks and hinges intact and there is a lock (no key). For the collector, this is the instrument to own. I have other examples listed on the website but this is by far the rarest and finest example I have seen for quite some time. There are very few William Simms instruments extant. Hasn’t been out of the box for 200 years (took me a 1/2 hour of prompting with a plastic lever to free it ) !!!

Apprenticed to his father in 1808, William was in business at his father’s jewelry store (soon converted to mathematical instruments) and worked solo for a decade (1815-1825) before his reputation for accurately dividing circles (new self-acting dividing engine) caught the eye of Edward Troughton. One of Simms’ first jobs was to re-divide an astronomical circle, at Greenwich, made by Troughton. The partnership lasted  until his death in 1860.

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CA ScientificaOpticae

Scientifica Opticae

Mark Hacking (Scientifica Opticae Inc.) has been an avid collector/dealer for over 30 years. A former Science teacher, he has an innate love for anything natural or mechanical. Specializing in optical (microscopes, telescopes), surveying, medical, weighing and drawing instruments, he is an active participant of the Scientific Instrument Fair in London. Living in Stratford, Ontario, Canada, with his wife and two children; Mark looks forward to meeting as many fellow collectors as possible, and has a worldwide following on eBay (Sciopti).

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