| RefNo | Title | Date |
| NLB/23/1/501 | Copy letter from Robert William Frederick Harrison, to Professor Jean Gaston Darboux, [Foreign Member, Royal Society], Academie des Sciences, Paris | 21 November 1901 |
| NLB/28/22 | Copy letter from Theodore E James to Messrs Harrison & Sons | 19 December 1903 |
| NLB/20/767 | Copy letter from Robert William Frederick Harrison, to Monsieur Professeur Jean Gaston Darboux, [Fellow of the Royal Society], Academie des Sciences, Paris | 4 July 1900 |
| NLB/22/176 | Copy letter from Robert William Frederick Harrison, to Professor Jean Gaston Darboux, [Foreign Member, Royal Society] | 19 March 1901 |
| NLB/23/1/432 | Copy letter from Robert William Frederick Harrison, to Professor Jean Gaston Darboux, [Foreign Member, Royal Society] | 12 November 1901 |
| NLB/8/1136 | Copy letter from Herbert Rix, to M le Professeur Jean Gaston Darboux, [Foreign Member, Royal Society], Faculte des Sciences, a la Sorbonne, Paris | 5 March 1894 |
| NLB/22/62 | Copy letter from Robert William Frederick Harrison, to M le Professeur Jean Gaston Darboux, [Foreign Member, Royal Society], Cabinet du Doyen, Faculte des Sciences, Paris | 25 February 1901 |
| NLB/22/100 | Copy letter from Sir Michael Foster, to Professor Jean Gaston Darboux, [Foreign Member, Royal Society], Secretary of the International Association of Academies | 4 March 1901 |
| NLB/23/1/754 | Copy letter from Joseph Larmor, to Monsieur le Professor Jean Gaston Darboux, [Foreign Member, Royal Society] | 16 January 1902 |
| NLB/23/1/670 | Copy letter from Robert William Frederick Harrison, to Monsieur le Professor Jean Gaston Darboux, [Foreign Member, Royal Society] | 23 December 1901 |
| NLB/23/2/40 | Copy letter from Sir Michael Foster, to Professor Jean Gaston Darboux, [Foreign Member, Royal Society] | 4 March 1901 |
| NLB/54/179 | Copy letter from [Robert William Frederick Harrison, Assistant Secretary of the Royal Society]; to Messrs Harrison & Sons | 26 February 1917 |
| NLB/54/138 | Copy letter from William Abbott Herdman, Foreigh Secretary of the Royal Society; to Professor Jean Gaston Darboux, FRS | 8 February 1917 |
| NLB/54/245 | Copy letter from Joseph John Thomson, President of the Royal Society; to Mr. F. A. A. Lacroix, Secretarie Perpetuel of the Academie des Sciences | 14 March 1917 |
| NLB/21/34 | Copy letter from Robert William Frederick Harrison, to Professor Jean Gaston Darboux, [Foreign Member, Royal Society], Academie des Sciences de l'Institute, Paris | 18 July 1900 |
| NLB/13/601 | Copy letter from Robert William Frederick Harrison, to Monsieur Professor Jean Gaston Darboux, [Foreign Member, Royal Society], Doyen de la Faculté des Sciences, 36 Rye Gay-Lussac, Paris | 14 October 1896 |
| NLB/28/15 | Copy letter from Robert William Frederick Harrison, to Professor [Jean Gaston] Darboux | 17 December 1903 |
| EC/1902/22 | Darboux, Jean Gaston: certificate of election to the Royal Society | |
| MC/17 | Volume 17 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1897-1899 |