| RefNo | Title | Date |
| EC/1909/19 | Orr, William McFadden: certificate of election to the Royal Society | |
| RR/19/73 | Referee's report by William McFadden Orr, on a paper 'On a form of the solution of Laplace's equation suitable for problems relating to two spheres' by George Barker Jeffery | 10 May 1912 |
| IM/003389 | Orr, William McFadden | nd |
| NLB/40/615 | Copy letter from Robert William Frederick Harrison to Professor [William McFadden] Orr FRS | July 1909 |
| NLB/40/710 | Copy letter from Robert William Frederick Harrison to Messrs Harrison & Sons | 16 July 1909 |
| RR/19/72 | Detailed referee's report by William McFadden Orr, on a paper 'On a form of the solution of Laplace's equation suitable for problems relating to two spheres' by George Barker Jeffery | [1912] |
| NLB/43/537 | Copy letter from Robert William Frederick Harrison, to Professor William McFadden Orr, Fellow of the Royal Society | 6 February 1911 |
| NLB/45/821 | Copy letter from Joseph Larmor to [William McFadden] Orr | 16 May 1912 |
| NLB/45/230 | Copy letter from Robert William Frederick Harrison to Professor W [William] McF [McFadden] Orr FRS | 23 January 1912 |
| NLB/45/683 | Copy letter from Robert William Frederick Harrison to Prof W [William] McF [McFadden], Orr FRS | 22 April 1912 |
| NLB/47/507 | Copy letter from Robert William Frederick Harrison to Professor W McFadden Orr FRS | 11 February 1913 |
| NLB/51/138 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society to Professor William McFadden Orr FRS | 28 December1914 |
| RR/17/404 | Referee's report by William McFadden Orr, on a paper 'On the flow of water through pipes and passages having converging or diverging boundaries' by A H Gibson | 13 January 1910 |
| NLB/61/372 | Copy letter from an unknown correspondent; to Professor [William McFadden] Orr, FRS | 24 June 1921 |
| NLB/55/574 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to [Professor William McFadden] Orr, FRS | 14 June 1918 |
| NLB/67/897 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Professor [William] McFadden Orr, FRS | 2 April 1925 |
| NLB/72/505 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Professor [William] McFadden Orr, FRS | 19 November 1929 |
| RR/19/62 | Referee's report by William McFadden Orr, on a paper 'The motion of viscous liquid due to uniform and periodic motion maintained over a segment of an infinite plane boundary' by W J Harrison | 8 November 1912 |
| RR/19/74 | Referee's report by William McFadden Orr, on a paper 'On the scattering and absorption of light in gaseous media, with applications to the intensity of sky radiation' by Louis Vessot King | 16 June 1912 |