Eyepiece micrometer inscribed E.2. in wood mount with brass frame and divided circle 1120 divisions, numbered 0 to 60) and steel screw, threads missing. Focal length 1.65 in
Dated 1780-1800, this eyepiece filar micrometer was made by the astronomer, William Herschel for the telescopes he used. In addition to building his own reflecting telescopes, Herschel made his own micrometers. This measuring instrument uses a set of fixed and moveable wires to determine angular distances in the eyepiece of the telescope. In operation, the calibrated handle was used to move the parallel wires delineating the object being measured. The distance was then calculated from the number turns of the handle that is attached to a fine threaded rod connected to the framework holding the moveable wires. Like Herschel's own eyepieces, the body of this instrument is made of cocoa, a tropical hardwood still used for woodwind instruments today.
- Object Number:
- filar micrometer
- natural sciences
- physical sciences
- furnishing and equipment
- measuring device - instrument
- micrometer - angle
- Mr John Herschel-Shorland
- Permanent collection
Cite this page
We encourage the use and reuse of our collection data.
Data in the title, made, maker and details fields are released under Creative Commons Zero
Descriptions and all other text content are licensed under a Creative Commons Attribution 4.0 licence
Download catalogue entry as json
Download manifest IIIF
Our records are constantly being enhanced and improved, but please note that we cannot guarantee the accuracy of any information shown on this website.