Accession No

2668

Brief Description

spectrometer micrometer, by Adam Hilger, English, 1875 (c)

Origin

England; London

Maker

Hilger, Adam

Class

optical

Earliest Date

1875

Latest Date

1875

Inscription Date

Material

metal (brass); glass

Dimensions

length 147mm; breadth 67mm; depth 96mm

Special Collection

Provenance

Transferred from Department of Chemistry, University of Cambridge, Cambridge, England, 1978. Physical Chemistry Department, Cambridge (unknown date)

Inscription

‘A. Hilger
London’

Description Notes

Micrometer for spectrometer, brass, on draw tube, with drumhead divided 0-100 by 1. Screw beneath adjusts height of lower wire. Small mirror on arm at side. Screw-in eyepiece with single draw tube.

References

Events

Description
Micrometer
Micrometers were used mainly by astronomers and microscopists to measure objects. They were first devised in about 1609 and used the exact number of turns of a screw to measure small distances. Micrometers were inserted into the path of a telescopes and microscopes, and were also used to accurately measure quadrant scales.

Early examples of the micrometers used in telescopes were calibrated geometrically using a piece of card at a distance of about 200m with lines of known separation on it. However, this introduced inaccuracies of a few seconds of arc due to the closeness of the card compared with the distance of real observations. It was not until 1672 that this problem was overcome and accurate calibration was possible.

18/10/2002
Created by: Saffron Clackson on 18/10/2002

FM:44825