| Reference number | HS/25/6/1 |
| Level | Item |
| Title | Copy letter, from Sir John Herschel to James David Forbes, dated at Slough |
| Creator | John Frederick William Herschel |
| Recipient | James David Forbes |
| Date | 3 March 1840 |
| Description | Copy letter in John Herschel's hand. Outlines theory behind and method for preparing thermographic paper, which allows observers to determine 'what share each ray of the spectrum bears in producing the observed total effects.' |
| Language | English |
| Extent | 2pp |
| Format | Manuscript |
| Place origin | Slough, Berkshire |
| Origin coordinates | 51.5082, -0.5954 |
| Digital images | View item on Science in the Making |
| Access status | Open |
| Related material | Original available: St. Andrews 12 |
| URL description | Also available on Epsilon |
| URL | https://epsilon.ac.uk/view/herschel/letters/Herschel3521
|
Fellows associated with this archive
| Code | Name | Dates |
| NA8238 | Herschel; Sir; John Frederick William (1792 - 1871); mathematician and astronomer | 1792 - 1871 |
| NA6280 | Forbes; James David (1809 - 1868); natural philosopher | 1809 - 1868 |