- Museum number
Oval brass plaque; slightly concave; four pin-holes; engraved with figure-of-eight for equation of time, labelled in French.
- Production date
Length: 124 millimetres
Width: 42 millimetres
- Curator's comments
For finding the time of mean solar noon, with the aid of a pinhole through which the sun shines. It is noon when the spot of light passing through the pinhole falls on the 'figure -of-eight' scale at the side corresponding to the date of use. Dates are marked at two-day intervals and numbered every four days, with the months and seasons named in French. In this instument the pinhole should be at a radius of 150 mm from the plaque. The equinoxes are at 20½ March and 23 September. The equation of time is zero at 15 April, 15 June, 1 September and 24 December.
For a complete instrument cf F.W. Cousins, Sundials (London 1969) p. 194
- Not on display
Latest: 2 (Jul 2015)
3 (Dec 1995) Incomplete.
- Acquisition date
- Acquisition notes
- The Ilbert Collection of clocks, prints and other related material was destined to be sold at Christie's auction house on 6th-7th November 1958. As a result of the generous donation of funds by Gilbert Edgar CBE the sale was cancelled and the material purchased privately from the beneficiaries of the Ilbert Estate.
Ilbert's watches were then acquired with further funds from Gilbert Edgar CBE, public donations and government funds. These were then registered in the series 1958,1201.
- Britain, Europe and Prehistory
- Registration number
- Additional IDs
Previous owner/ex-collection number: CAI.2430 (Ilbert Collection)