Benjamin Ayres (died c. 1775) was an English instrument maker. Ayres may have been related to the scientist Thomas Ayres who was nominated to the

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

in 1707 and who was later involved in a joint-stock company to exploit the

Newcomen steam engine The atmospheric engine was invented by Thomas Newcomen in 1712, and is sometimes referred to as the Newcomen fire engine (see below) or Newcomen engine. The engine was operated by condensing steam being drawn into the cylinder, thereby creating ...

. Ayres was an apprentice and brother-in-law of

Jonathan Sisson Jonathan Sisson (1690 – 1747) was an English instrument maker, the inventor of the modern theodolite with a sighting telescope for surveying, and a leading maker of astronomical instruments. Career Jonathan Sisson was born in Lincolnshire ar ...

London London is the Capital city, capital and List of urban areas in the United Kingdom, largest city of both England and the United Kingdom, with a population of in . London metropolitan area, Its wider metropolitan area is the largest in Wester ...

. Ayres was active between 1731 and 1775, making mathematical instruments and compasses. He worked in

Amsterdam Amsterdam ( , ; ; ) is the capital of the Netherlands, capital and Municipalities of the Netherlands, largest city of the Kingdom of the Netherlands. It has a population of 933,680 in June 2024 within the city proper, 1,457,018 in the City Re ...

from 1743 onward, and sold octants to the

Dutch East India Company The United East India Company ( ; VOC ), commonly known as the Dutch East India Company, was a chartered company, chartered trading company and one of the first joint-stock companies in the world. Established on 20 March 1602 by the States Ge ...

. His devices incorporate technical innovations introduced by Sisson, which were copied by others only after 1750. Some of them were included in the collection of instruments made by

Gerard Arnout Hasselaer Gerard Arnout Hasselaer (20 February 1698, Amsterdam - 12 July 1766, Heemstede) was a burgomaster and counsellor of the city of Amsterdam, and a Director of the Dutch East India Company. Some historians have said he was an able regent. Others have ...

, a board member of the company. Hasselaer had connections with both Ayres and Sisson. In 1734 Caleb Smith invented a "sea quadrant" using an unsilvered glass mirror to reflect the image of the sun into the telescope. Ayres produced an instrument based on this design mounted on gimbals over a magnetic compass, with a spirit level for use when the horizon was not visible, the whole contained in a solid wooden case. Around 1750 Ayres invented and made a sailors' arithmetical instrument, now held in the University Museum of Utrecht. It consisted of a brass disk on which a number of circular logarithmic scales were inscribed, with two radial wires that could each be locked to a point on the circumference. Using this instrument, a sailor could perform various trigonometric calculations by setting the wire to the position of the argument on one of the circular scales and reading the result from another of the circular scales. Ayres made fine, large

Azimuth compass An azimuth compass (or azimuthal compass) is a nautical instrument used to measure the magnetic azimuth, the angle of the arc on the horizon between the direction of the Sun or some other celestial object and the magnetic north. This can be compar ...

es, used in determining how much the magnetic compass deviated from true north. A brass mariner's compass in gimbals set in a mahogany box, made by Ayres in Amsterdam around 1775, is said to have been the property of Sir

Isaac Newton Sir Isaac Newton () was an English polymath active as a mathematician, physicist, astronomer, alchemist, theologian, and author. Newton was a key figure in the Scientific Revolution and the Age of Enlightenment, Enlightenment that followed ...

References

Citations Sources * * * * * * {{DEFAULTSORT:Ayres, Benjamin 1775 deaths English scientific instrument makers Year of birth unknown