| Reference number | NLB/56/441 |
| Alternative reference number | NLB/56 p259 |
| Level | Item |
| Title | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Thomas Bon Dapray Esquire; The Christiana Apt. 21, 1829 California Street, Washington |
| Date | 13 February 1919 |
| Description | Informs Mr. Thomas Bon Dapray that he is not aware of an invention called 'The Searchlight', however, that the description given corresponds with 'Thermophones', an invention laid out in a paper by M. De Lange. Notes that an abstract of this paper was published in the 'Proceedings' and can be found in volume 92 (A). |
| Extent | 1p |
| Format | Carbon |
| Access status | Open |