| RefNo | AP/28/8/1 |
| Level | Item |
| Title | Unpublished manuscript, 'On magnetic variation' by John George Hartley |
| Creator | Hartley; John George (fl 1846) |
| Date | August 1845 |
| Description | Hartley attempts to produce an estimation of the precise value of the equinoctial or astronomical year.
Followed by a covering letter addressed to P M [Peter Mark] Roget.
Subject: Magnetism
Received 16 October 1846. |
| Extent | 8p |
| Format | Manuscript |
| PhysicalDescription | Ink on paper |
| AccessStatus | Open |