| RefNo | PP/12/9/2 |
| Previous numbers | PP/44/9 |
| Level | Item |
| Title | Figures, photographic plates by C [Charles] Pritchard |
| Date | 1888 |
| Description | Two drawings, labelled figures 1-2, of photographic plates of stars. Each figure has a corresponding engraved print.
Figure 1 shows a photographic plate ABCD where AB is four inches, and subtends an angle of 1° 55' at the centre of the 15/120-inch mirror. A pair of stars of approximately the seventh magnitude is pictured near the centre of the plate with an exposure of five minutes. Pritchard describes the method for taking the photographs, in which 'The telescope was then moved approximately fifteen minutes to the south, and a second photograph taken, by which this same pair was removed to (b). This process was repeated again and again in northerly, easterly, and westerly directions, till after thirteen exposures this same pair of stars was dotted about the plate as in the diagram.' Figure 1 shows a photographic plate of 'nearly three inches square, subtendingan angle of 1° 56'. The pair of stars selected consisted of Atlas and Pleione, and these by the motion of the telescope were made to occupy successively the positions indicated in the subjoined diagram, which will be understood from the description of the former.'
Subject: Optics
The prints were published in volume 44 of the Proceedings of the Royal Society alongside the paper 'Report on the capacities, in respect of light and photographic action, of two silver on glass mirrors of different focal lengths'. |
| Extent | 4p |
| Format | Drawing |
| Print |
| PhysicalDescription | Ink and graphite pencil on paper |
| Digital images | View item on Science in the Making |
| AccessStatus | Open |
| RelatedMaterial | DOI: 10.1098/rspl.1888.0019 |
Fellows associated with this archive
| Code | PersonName | Dates |
| NA5459 | Pritchard; Charles (1808 - 1893) | 1808 - 1893 |