Accession No

6227

Brief Description

50cm linear precision measurement scale for calibration, later used by Hilger and Watts Ltd., Watts Division, by Adam Hilger Ltd., c. 1925

Origin

England; London

Maker

Adam Hilger Ltd.

Class

metrology; engineering

Earliest Date

1904

Latest Date

1927

Inscription Date

Material

metal (steel, brass); wood (mahogany); cloth (felt)

Dimensions

[box] length 645mm; depth 118mm; height 102mm [scale] length 582mm; depth 59mm; height 44mm

Special Collection

Provenance

Donated on or before 27/05/2008.

Inscription

[embossed on side of scale]
NPL
27
54478
[Label on box]
No. 27 - 54475
CALIBRATION
SCALE
[unclear] L76/L13

Description Notes

50cm linear precision measurement scale for calibration, by Adam Hilger, c. 1925.

Trough shaped heavy steel channel, containing a thin, highly polished linear steel strip exactly 50cm long. This strip has a very finely marked scale (graduated in 1cm intervals) marked on it. Both ends of the trough have a hole in, with one end also having brass screws in place.

Scale sits inside fitted mahogany box, with felt padding.

Also included with the scale are three calibration certificates, confirming the accuracy of the scale as a calibration device. The first two of these certificates are issued by the National Physical Laboratory to Adam Hilger, Ltd. The earlier of these is dated 6/5/1927 and says: “Nature of Test:- Determination of the mean thermal coefficient of expansion, and a calibration of the centimetre intervals throughout” and gives the coefficient of expansion as 0.00001055 per 1oC, and also gives a table indicating the length in cm of each marked interval on the scale, to five decimal places. The second certificate, dated 11/3/1932, is also to determine the accuracy of the graduated scale to five decimal places. The third certificate, dated 13/5/1953, is issued by Hilger & Watts Ltd. and checks the scales accuracy against a linear dividing engine, and includes a graph of all three tests.

References

Events