Accession No

2162

Brief Description

miner's dial, by Davis and Son, English, 1870 (c)

Origin

England; Derby

Maker

Davis and Son

Class

surveying

Earliest Date

1870

Latest Date

1870

Inscription Date

Material

metal (alloy, silver); glass

Dimensions

length 304mm; height 172mm; breadth 174mm

Special Collection

Provenance

Transferred from Department of Geography, University of Cambridge, Cambridge, England, 05/1969.

Inscription

‘Davis and Son Derby’ (on compass face)
‘894 Pat. No. 2084’ (on socket)

Description Notes

Metal alloy. Central compass. Silvered scales - outer graduated to 0-360˚ clockwise to 1˚ and read by vernier to 3’ of arc. Graduations extend to inner edge of ring and are read by the needle. Base of compass graduated 0-90-0˚ every 10˚ and marked with the cardinal points. Locking bar. Two spirit levels in face of compass set with their axes mutually perpendicular. Compass ring rotates within the box for measuring azimuth angles independently of the needle, controlled by clamp and azimuth motion tangent screw below box. Rocking circle pivots externally on horizontal bearings to the compass box carrying slit/window and pinhole/circle sights. Locking bar holds rocking circle horizontal. Angle measured by vertical semi-circle, which rocks with circle. Graduated 90-0-90˚ and 100-0-100˚ difference of hypotenuse and base read by arm. Compass box. The whole rotates about a vertical axis with clamp. Socket and clamp for attachment to tripod. (Compass glass missing).

References

Events