Jesse Ramsden (6.10.1735-5.11.1800) was an English mechanic and optician, a well-known maker of physical instruments, and a Fellow of the Royal Society (1786). He was born in Halifax. In 1755 he moved to London and worked as a clerk. In 1758 he became an apprentice to a maker of mathematical instruments, and in 1762 he opened his own workshop. He developed a technology that enabled him to raise the accuracy of the astronomical, physical and navigational instruments he made. In the workshop he founded, about 1000 theodolites, balances, barometers, sextants and micrometers had been made by 1789. Also built were an electrical machine with glass plates (1766, the Ramsden machine), a dividing engine, a micrometer microscope, an achromatic telescope, an eyepiece consisting of two plano-convex lenses separated by an air gap (the Ramsden eyepiece) and others. He supplied many astronomical observatories of Europe with achromatic telescopes and other instruments.
Member of the St Petersburg Academy of Sciences (1794). Copley Medal (1795).