Accession No

1670

Brief Description

horizontal dial, by Jacob Abraham, English, c. 1816

Origin

England; Bath

Maker

Abraham, Jacob

Class

dials

Earliest Date

1816

Latest Date

1816

Inscription Date

Material

metal (brass, steel); glass; wood (mahogany); paper

Dimensions

case length 135mm; breadth 131mm; thickness 31mm

Special Collection

Fitzwilliam collection

Provenance

On loan from The Fitzwilliam Museum, University of Cambridge. From the Spencer George Percival Bequest, 1923.

Inscription

‘Abraham
BATH’ (hour ring)

Description Notes

Horizontal dial by Abraham, c.1816. In hinged one-piece mahogany case. Set into the base is a brass hour ring surmounting the compass bowl. Scale divided [IV 1/2] V - XII, I - VII [VII 1/2], numbered by I, subdivided to 5 minutes; with open gnomon for 52˚ N. Paper compass card with 32-point rose. Fleur-de-lys for North. Degree scale divided [0] - 360˚, numbered by 10˚, subdivided to 1˚. (Needle marked ‘N’ and ‘S’; needle arrest mechanism; 31-1-2000). MS label in lid:
‘To rectify Compass to find the hour of the
day. Set off 28˚ West equal 1 hour
5[?] minutes the difference in this latitude
between Magnetic & true North
Bristol &
Bideford 1816’.

Condition: good; complete.

References

Events

Description
The horizontal dial is the most common form of sundial. The portable version proved very popular with the upper classes during the 19th Century. During this period it could best be described as the wristwatch of its day.

The hour lines are engraved onto a horizontal surface, with a gnomon (pointer) in the centre. Seasonal variations (caused by the earth’s orbit being elliptical, not circular) have to be compensated for, as they can affect the raw reading by up to 18 minutes.
18/10/2002
Created by: Saffron Clackson and Boris Jardine on 18/10/2002

FM:43227