Public Domain Mark
You can use this work for any purpose without restriction under copyright law. Read more about this licence.
Credit
A treatise of such mathematical instruments as are usually put into a portable case, containing their various uses. In arithmetic, geometry, trigonometry, architecture, surveying, gunnery, etc., with a short account of the authors who have treated on the proportional compasses and sector. To which is now added an appendix containing the description and use of the gunner's callipers / [J. Robertson]. Public Domain Mark. Source: Wellcome Collection.