Micrometer Eyepiece with Case, by Thomas Jones, London, Early 19th Century

A telescope micrometre eyepiece with an exterior thread which screws into the end of a telescope tube for measuring angles. Behind the eyepiece moves a track which is operated by a rack-and-pinion, and this carries the micrometre advances. On the left it is marked 'A' and on the right 'B'. A hand screw at either end is connected to a wheel marked from 0 - 100 byones, each wheel with a copper alloy pointer. The micrometre is housed in a mahogany case with two handles, a hinged lid, two swing clasp fastenings, and a lock mechanism. Inside, there are wooden fittings, one of which is removable. The wooden fittings are lined with green felt. Stored inside the case are: an extra eyepiece; a glass shade; and two screws.