Accession No

6111

Brief Description

home-made prototype of the Dollar integrating micometer for petrological use, by A. T. J. Dollar, English, c. 1935

Origin

England; Cambridge

Maker

Dollar, A. T. J.

Class

metrology; microscopes; earth sciences

Earliest Date

1935

Latest Date

1936

Inscription Date

Material

wood; metal (brass, steel, copper); paper; plastic

Dimensions

Length 295mm; width 295mm; height 85mm

Special Collection

Provenance

Donated on or before 15/06/2007.

Inscription

Description Notes

Home-made prototype of the Dollar integrating micometer for petrological use, by A. T. J. Dollar, English, c. 1935. [See Wh.6132 for Unicam production version.]

Micrometer assembly sits above a steel rule on wooden base on micrometer, marked in 1/2 mm up to 5cm, and then in mm up to 15mm. Rule also maked in inches, in 1/32 up to 3”, then in 1/64 up to 3 1/2”, and then in 1/16 up to 6”. Black plastic knob moves assembly up and down a screw running length of rule.

Spaced out along the length of the assembly are five miniature, unmarked versions of what would be the six gradated drums in the final version. The sixth of these drums, a full-sized prototype, marked from 1-17 around its circumference, is not attached to the object. Pencil markings on wooden bar along length of assembly indicate where there would be properly measured markings in final version.

Unattached is a lens, which would have been used to demonstrate how the instrument is used in conjunction with a microscope for highly accurate measurements.

Condition: fair; instrument is not fully assembled, with some knobs and screws unattached, and the manner of correct assembly is not clear.

References

Events