| Reference number | Title | Date |
| NLB/9/998 | Copy letter from Theodore E James, to Professor James William Helenus Trail, Fellow of the Royal Society | 14 August 1894 |
| NLB/23/1/839 | Copy letter from an unknown correspondent, to Professor James William Helenus Trail, [Fellow of the Royal Society] | 4 February 1902 |
| NLB/34/514 | Copy letter from Archibald Geikie, to Professor James William Helenus Trail, Fellow of the Royal Society | 1 February 1907 |
| NLB/34/620 | Copy letter from Robert William Frederick Harrison, to Professor James William Helenus Trail, Fellow of the Royal Society | 16 February 1907 |
| NLB/34/550 | Copy letter from Robert William Frederick Harrison, to Professor James William Helenus Trail, Fellow of the Royal Society | 6 February 1907 |
| NLB/57/509 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Sir David Prain, FRS, CMG | 20 November 1919 |
| NLB/57/231 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to unknown correspondent | 22 September 1919 |
| NLB/57/379 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor I [Isaac] Bayley Balfour, FRS | 29 October 1919 |
| RR/17/166 | Referee's report by James William Helenus Trail, on a paper 'Longitudinal symmetry in Phanerogamia' by Percy Groom | [February 1907] |
| EC/1893/14 | Trail, James William Helenus: certificate of election to the Royal Society | |
| NLB/57 | New Letter Book volume 57, copy letters sent from Royal Society administration | 27 June 1919-27 February 1920 |
| MC/24/114 | Letter from [David] Prain, Royal Gardens, Kew, to Mr [Robert] Harrison, Assistant Secretary, The Royal Society, Burlington House, Piccadilly | 5 May 1909 |
| MC/24/112 | Letter from [David] Prain, Royal Gardens, Kew, to Mr [Robert] Harrison, Assistant Secretary, The Royal Society, Burlington House | 13 March 1909 |
| MC/24/187 | Letter from James [William Helenus] Trail, Marischal College, Aberdeen, to [David] Prain, [Royal Society] | 12 May 1909 |