| RefNo | Title | Date |
| EC/1894/08 | Callendar, Hugh Longbourne: certificate of election to the Royal Society | |
| MC/19/160 | Letter from [Hugh Longbourne] Callendar, Board of Education, Royal College of Science, London, to the Royal Society | 24 August 1904 |
| IM/000704 | Callendar, Hugh Longbourne | 2001 |
| RR/26/34 | Referee's report by Hugh Longbourne Callendar, on a paper 'Notes upon evaporation and the discharge of steam from orifices' by W Geoffrey Duffield | [July 1921] |
| NLB/34/59 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 21 November 1906 |
| NLB/4/972 | Copy letter from Herbert Rix, to Hugh Longbourne Callendar, 2 Princes Mansions, Victoria Street, S.W. | 12 December 1890 |
| NLB/6/233 | Copy letter from Herbert Rix, to Hugh Longbourne Callendar, 2 Princes Mansions, Victoria Street, S.W. | 30 March 1892 |
| RR/18/9 | Referee's report by Hugh Longbourne Callendar, on a paper 'The depression of freezing point in very dilute aqueous solutions' by T G Bedford | March 1910 |
| NLB/5/4 | Copy letter from an unknown correspondent, to Messrs West, Newman & Company, 54, Hatton Garden | 14 February 1891 |
| NLB/5/3 | Copy letter from Herbert Rix, to Hugh Longbourne Callendar, 2 Princes Mansions, Victoria Street | 13 February 1891 |
| NLB/5/646 | Copy letter from Theodore E James, to Hugh Longbourne Callendar | 1 August 1891 |
| NLB/9/995 | Copy letter from Theodore E James, to Messrs Harrison & Sons | 14 August 1894 |
| NLB/9/249 | Copy letter from Herbert Rix, to Lord Rayleigh [John William Strutt], Secretary, Royal Society | [20 April 1894] |
| NLB/9/303 | Copy letter from Herbert Rix, to Ernest Howard Griffiths | 27 April 1894 |
| NLB/5/672 | Copy letter from Theodore E James, to John Evans, Treasurer, Royal Society | 1 September 1891 |
| NLB/13/469 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, 62 Hutchinson Street, Montreal, Canada | 21 September 1896 |
| RR/15/164 | Referee's report by Osborne Reynolds, on a paper 'Continuous electrical calorimetry' by Hugh Longbourne Callendar | 9 January 1902 |
| RR/15/115 | Referee's report by Hugh Longbourne Callendar, on the Bakerian Lecture 'The specific heat of metals and the relation of specific heat to atomic weight. (with an addendum by Prof. Perry)' by Professor William Augustus Tilden | February 1900 |
| RR/16/243 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the electric effect of rotating a dielectric in a magnetic field' by Harold Albert Wilson | 25 May 1904 |
| RR/16/365 | Referee's report by Hugh Longbourne Callendar, on a paper 'The compressibility of gases between one atmosphere and half an atmosphere of pressure' by Robert John Strutt, Lord Rayleigh | 3 February 1905 |
| NLB/44 | New Letter Book volume 44, copy letters sent from Royal Society administration | 12 April-4 December 1911 |
| NLB/30/889 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 6 June 1905 |
| RR/15/287 | Referee's report by Hugh Longbourne Callendar, on a paper 'The electrical conductivity of air and salt vapours' by Harold Albert Wilson | April 1901 |
| RR/16/137 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the discharge of electricity from hot Platinum' by Dr H A Wilson | June 1903 |
| RR/15/393 | Referee's report by Hugh Longbourne Callendar, on a paper 'The measurements of temperature. Parts I-III' by Morris William Travers, George Senter and Adrien Jaquerod | July 1902 |
| RR/17/73 | Referee's report by Hugh Longbourne Callendar, on a paper 'Researches on explosives.—Part IV' by Andrew Nobel | [July 1906] |
| RR/16/118 | Referee's report by Hugh Longbourne Callendar, on a paper 'The vapour pressure of liquid Oxygen on the scale of the constant volume Oxygen thermometer filled at different initial pressures' by Morris William Travers and Charles J Fox | August 1903 |
| RR/17/103 | Referee's report by Hugh Longbourne Callendar, on a paper 'On a static method of comparing the densities of gases' by Richard Threlfall | [April 1906] |
| RR/16/289 | Referee's report by Hugh Longbourne Callendar, on a paper 'The refractive index of gaseous fluorine' by Clive Cuthbertson and E B R Prideaux | June 1905 |
| RR/16/107 | Referee's report by Hugh Longbourne Callendar, on a paper 'Studies in magnetic testing' by George Frederick Charles Searle | January 1904 |
| RR/15/394 | Second referee's report by Hugh Longbourne Callendar, on a paper 'The measurements of temperature. Parts I-III' by Morris William Travers, George Senter and Adrien Jaquerod | 4 July 1902 |
| RR/16/255 | Referee's report by Hugh Longbourne Callendar, on a paper 'Explosions of mixtures of coal-gas and air in a close vessel' by Leonard Bairstow and A D Alexander | March 1905 |
| RR/16/104 | Referee's report by Hugh Longbourne Callendar, on a paper 'The determination of specific heats, especially at low temperatures' by H E Schmitz | March 1903 |
| RR/16/90 | Referee's report by Hugh Longbourne Callendar, on a paper 'The evaporation of water in a current of air' by Edgar Philip Perman | March 1903] |
| RR/16/183 | Referee's report by Hugh Longbourne Callendar, on a paper 'The optical properties of vitreous silica' by J W Gifford and William Ashwell Shenstone | February 1904 |
| NLB/17/559 | Copy letter from Robert William Frederick Harrison, to Herbert Rix, Headland Cottage, Limpsfied, Surrey | 18 November 1898 |
| RR/16/147 | Referee's report by Hugh Longbourne Callendar, on a paper 'Saturated solutions' by Randal Thomas Mowbray Rawdon Berkeley | April 1904 |
| RR/16/189 | Referee's report by Hugh Longbourne Callendar, on a paper 'The high temperature standards of the National Physical Laboratory. An account of a comparison of Platinum Thermometers and Thermo-junctions with the Gas-thermometer' by Dr John Allen Harker | February 1904 |
| RR/16/342 | Referee's report by Hugh Longbourne Callendar, on a paper 'The flow of the River Thames in relation to British pressure & rainfall changes' by Sir Joseph Norman Lockyer and Dr W J S Lockyer | 5 June 1905 |
| RR/16/394 | Referee's report by Hugh Longbourne Callendar, on a paper 'The vapour pressure in equilibrium with substances holding varying amounts of moisture' by Professor Frederick Thomas Trouton and Miss B Pool | January 1906 |
| RR/18/113 | Referee's report by Arthur William Rucker, on a paper 'On the variation of the specific heat of water, with experiments by a new method' by Hugh Lonbourne Callendar | January 1912 |
| RR/17/102 | Referee's report by Hugh Longbourne Callendar, on a paper 'Calcium as an absorbent of gases for the production of high vacua and spectroscopic research' by Frederick Soddy | [September 1906] |
| RR/17/19 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the specific heat of, heat flow from, and other phenomena of, the working fluid in the cylinder of the internal combustion engine' by Dugald Clerk | [March 1906] |
| RR/17/52 | Referee's report by Hugh Longbourne Callendar, on a paper 'Explosions of coal-gas and air' by Bertram Hopkinson | [February 1906] |
| RR/16/350 | Referee's report by Hugh Longbourne Callendar, on a paper 'Researches on Explosives. Part III' by Sir Andrew Noble | June 1905 |
| RR/17/248 | Referee's report by Hugh Longbourne Callendar, on a paper 'Contributions to the osmotic theory of solution' by Randal Thomas Mowbray Berkeley and C V Burton | 5 December 1908 |
| NLB/17/471 | Copy letter from Robert William Frederick Harrison, to Theodore E James, to Messrs Harrison & Sons | 7 November 1898 |
| NLB/17/459 | Copy letter from Arthur William Rucker, to Richard Tetley Glazebrook, Fellow of the Royal Society | 3 November 1898 |
| NLB/17/529 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 14 November 1898 |
| NLB/17/557 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, University College, Gower Street, W.C. | 18 November 1898 |
| NLB/21/329 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, [Fellow of the Royal Society] | 1 November 1900 |
| NLB/18/164 | Copy letter from Arthur William Rucker, to Professor Callendar, Fellow of the Royal Society | 27 January 1899 |
| NLB/19/257 | Copy letter from Robert William Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 20 July 1899 |
| NLB/20/501 | Copy letter from Theodore E James, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | [7 May 1900] |
| NLB/20/135 | Copy letter from Robert William Frederick Harrison, to Professor George Carey Foster, Fellow of the Royal Society | 10 February 1900 |
| NLB/20/502 | Copy letter from Arthur William Rucker, to Hugh Longbourne Callendar, [Fellow of the Royal Society] | 7 May 1900 |
| NLB/20/741 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 28 June 1900 |
| NLB/20/709 | Copy letter from Robert William Frederick Harrison, to Dr Dukinfield Henry Scott, Fellow of the Royal Society | 22 June 1900 |
| NLB/21/319 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 29 October 1900 |
| NLB/21/114 | Copy letter from Theodore E James, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 30 July 1900 |
| NLB/22/355 | Copy letter from Robert William Frederick Harrison, to Professor [Hugh Longbourne] Callendar, Fellow of the Royal Society | 30 April 1901 |
| NLB/23/2/166 | Copy letter from Joseph Larmor, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 20 February 1902 |
| NLB/22/363 | Copy letter from Robert William Frederick Harrison, to Professor [Hugh Longbourne] Callendar, Fellow of the Royal Society | 2 May 1901 |
| NLB/21/546 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 7 December 1900 |
| NLB/21/399 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 13 November 1900 |
| NLB/22/818 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, [Fellow of the Royal Society] | 25 July 1901 |
| NLB/24/305 | Copy letter from Robert William Frederick Harrison, to Professor [Hugh Longbourne] Callendar, Fellow of the Royal Society | 23 April 1902 |
| NLB/23/1/755 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Royal College of Science, South Kensington, S.W. | 16 January 1902 |
| NLB/23/2/490 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society. | 3 June 1904 |
| NLB/24/222 | Copy letter from Theodore E James, to Professor [Hugh Longbourne] Callendar, Fellow of the Royal Society | 8 April 1902 |
| NLB/24/75 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 25 February 1902 |
| NLB/27/615 | Copy letter from Joseph Larmor, to Professor Hugh Longbourne Callendar, [Fellow of the Royal Society] | 29 October 1903 |
| NLB/54/27 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 24 January 1917 |
| NLB/27/465 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 2 October 1903 |
| NLB/29/79 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Sectional Committee | 1 July 1904 |
| NLB/30/179 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 8 February 1905 |
| NLB/34/110 | Copy letter from Robert William Frederick Harrison, to Professor [Hugh Longbourne] Callendar, Fellow of the Royal Society | 29 November 1906 |
| NLB/30/7 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 16 January 1905 |
| NLB/30/209 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 13 February 1905 |
| NLB/30/198 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 13 February 1905 |
| NLB/30/141 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 3 February 1905 |
| NLB/29/148 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 15 July 1904 |
| NLB/30/302 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 1 March 1905 |
| NLB/30/314 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 3 March 1905 |
| NLB/30/271 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 22 February 1905 |
| NLB/30/437 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 23 March 1905 |
| NLB/30/460 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 28 March 1905 |
| NLB/28/399 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 1 March 1904 |
| NLB/30/627 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 19 April 1905 |
| NLB/28/488 | Copy letter from [Robert William Frederick Harrison], to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 14 March 1904 |
| NLB/29/343 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 27 September 1904 |
| NLB/42/425 | Copy letter from Joseph Larmor to H [Hugh] L [Longbourne] Callendar | 10 June 1910 |
| NLB/28/555 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 29 March 1904 |
| NLB/34/98 | Copy letter from Joseph Larmor, to Professor [Hugh Longbourne] Callender, [Fellow of the Royal Society] | 27 November 1906 |
| NLB/28/543 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, 2 Chester Place, Regents Park | 26 March 1904 |
| NLB/28/639 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 22 April 1904 |
| NLB/30/890 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | [6] June 1905 |
| NLB/33/302 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 31 July 1906 |
| NLB/31/774 | Copy letter from Robert Frederick William Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 13 November 1905 |
| NLB/31/249 | Copy letter from Joseph Larmor, to Hugh Longbourne Callendar, [Fellow of the Royal Society] | 13 July 1905 |
| NLB/29/590 | Copy letter from Joseph Larmor, to Hugh Longbourne Callendar, [Fellow of the Royal Society] | [November 1904] |
| NLB/33/220 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 17 July 1906 |
| NLB/31/61 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 16 June 1905 |
| NLB/31/448 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 21 September 1905 |
| NLB/31/579 | Copy letter from an unknown correspondent, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 13 October 1905 |
| NLB/31/665 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 28 October 1905 |
| NLB/33/345 | Copy letter from A H White, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 9 August 1906 |
| NLB/33/21 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Sectional Committee | 18 June 1906 |
| NLB/32/550 | Copy letter from [Robert William Frederick Harrison], to [Messrs Harrison & Sons] | 30 March 1906 |
| NLB/33/495 | Copy letter from Joseph Larmor, to Professor Hugh Longbourne Callendar, [Fellow of the Royal Society] | 12 September 1906 |
| NLB/33/771 | Copy letter from Joseph Larmor, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 1 November 1906 |
| NLB/32/808 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 28 May 1906 |
| NLB/33/810 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Chairman of the Physiology Sectional Committee | 7 November 1906 |
| NLB/34/135 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 4 December 1906 |
| NLB/34/265 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 18 December 1906 |
| NLB/37/410 | Copy letter from Robert William Frederick Harrison to Professor [Joseph] Larmor, John's Cambridge | March 1908 |
| NLB/37/263 | Copy letter from Robert William Frederick Harrison to Harrison & Sons | 24 February 1908 |
| NLB/38/221 | Copy letter from Joseph Larmor, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 2 July 1908 |
| NLB/37/322 | Copy letter from Robert William Frederick Harrison to Messrs Harrison & Sons, St Martin's Lane, WC | 2 March 1908 |
| NLB/39/391 | Copy letter from Joseph Larmor to [Hugh Longbourne] Callendar | 15 January 1909 |
| NLB/39/64 | Copy letter from Robert William Frederick Harrison to Professor Callendar | 19 November 1908 |
| NLB/36/874 | Copy letter from Robert William Frederick Harrison, to A E Thompson, care of Messrs Willans & Robinson, Limited, Victoria Works, Rugby | 6 January 1908 |
| NLB/39/136 | Copy letter from Joseph Larmor to Professor Callendar | 1 December 1908 |
| NLB/39/589 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Loungbourne] Callendar, Fellow of the Royal Society | 10 February 1909 |
| NLB/39/311 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar, Fellow of the Royal Society | 1 January 1909 |
| NLB/39/300 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar, Fellow of the Royal Society | 23 December 1908 |
| NLB/39/480 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar, Fellow of the Royal Society | 26 January 1909 |
| NLB/40/445 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh Longbourne] Callendar FRS | 9 June 1909 |
| NLB/43/332 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 13 December 1910 |
| NLB/42/57 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar, FRS, Chairman of the Physics and Chemistry Committee | 17 March 1910 |
| NLB/42/611 | Copy letter from Robert William Frederick Harrison to Professor H [Hug] L [Longbourne] Callendar FRS | 15 July 1910 |
| NLB/43/195 | Copy letter from Joseph Larmor, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 17 November 1910 |
| NLB/41/206 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callender, Fellow of the Royal Society | 1 November 1909 |
| NLB/43/584 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 16 January 1911 |
| NLB/43/115 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 7 November 1910 |
| NLB/43/415 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 6 January 1911 |
| NLB/42/289 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 9 May 1910 |
| NLB/42/358 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Calldenar FRS, 49 Grange Road, Ealing, W | 27 May 1910 |
| NLB/45/510 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 19 March 1912 |
| NLB/43/127 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 8 November 1910 |
| NLB/42/501 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 22 June 1910 |
| NLB/41/693 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 7 February 1910 |
| NLB/43/301 | Copy letter from Joseph Larmor, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 8 December 1910 |
| NLB/42/785 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 11 October 1910 |
| NLB/42/729 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 28 September 1910 |
| NLB/44/512 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar, Chairman of the Physics & Chemistry Sectional Committee | 26 July 1911 |
| NLB/43/203 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 18 November 1910 |
| NLB/42/748 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 30 September 1910 |
| NLB/44/5 | Copy letter from Robert William Frederick Harrison to The Chairman, Physicis and Chemistry Sectional Committee [Hugh Longbourne Callendar] | 12 April 1911 |
| NLB/44/459 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar, Chairman, Physics & Chemistry Committee | 13 July 1911 |
| NLB/43/251 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 30 November 1910 |
| NLB/43/92 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 4 November 1910 |
| NLB/44/226 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar, Chairman of the Physics and Chemistry Committee | 27 May 1911 |
| NLB/43/267 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 2 December 1910 |
| NLB/44/288 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 8 June 1911 |
| NLB/44/315 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 15 June 1911 |
| NLB/44/301 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 10 June 1911 |
| NLB/44/346 | Copy letter from Robert William Frederick Harrison to The Chairman P [Physics] and C [Chemistry] Committee, Professor [Hugh Longbourne] Callendar FRS [Fellow of the Royal Society] | 21 June 1911 |
| NLB/43/367 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Sectional Committee | 16 December 1910 |
| NLB/43/523 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 3 February 1911 |
| NLB/44/550 | Copy letter from Joseph Larmor to Professor H [Hugh] L [Longbourne] Callendar FRS | 4 August 1911 |
| NLB/44/689 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar, Chairman of the Physics & Chemistry Sectional Committee | 20 October 1911 |
| NLB/43/679 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callender, Fellow of the Royal Society | 9 March 1911 |
| NLB/44/652 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 9 October 1911 |
| MC/26/46 | Letter from [Hugh Longbourne] Callendar, Imperial College of Science and Technology, Royal College of Science, South Kensington, London, S.W, to [Robert] Harrison, [Royal Society] | 15 June 1911 |
| NLB/44/783 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS, Chairman, Physics & Chemistry Sectional Committee | 10 November 1911 |
| NLB/44/805 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne Callendar FRS, Chairman of the Physics & Chemistry Sectional Committee | 14 November 1911 |
| NLB/45/217 | Copy letter from Robert William Frederick Harrison to [Hugh Longbourne] Callendar | 22 January 1912 |
| NLB/45/64 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 15 December 1911 |
| NLB/45/372 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 23 February 1912 |
| NLB/45/336 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 15 February 1912 |
| NLB/45/314 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 10 February 1912 |
| NLB/45/322 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 12 February 1912 |
| NLB/47/471 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 5 February 1913 |
| NLB/48/673 | Copy letter from A H White, to Professor [Hugh Longbourne] Callendar, Fellow of the Royal Society | 16 September 1913 |
| NLB/50/156 | Copy letter from Robert William Frederick Harrison, to Professor [Hugh Longbourne] Callendar, Fellow of the Royal Society | 9 May 1914 |
| NLB/50/92 | Copy letter from Robert William Frederick Harrison, to Professor [Hugh Longbourne] Callendar, Fellow of the Royal Society | 29 April 1914 |
| NLB/51/458 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society to Professor Hugh Longbourne Callendar FRS | 23 March 1915 |
| NLB/64/31 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, FRS | 22 January 1923 |
| MC/30/37 | Letter from [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, W, to [Robert] Harrison, [Royal Society] | 23 March 1915 |
| NLB/51/578 | Copy letter from Arthur Schuster, Secretary of the Royal Society to Professor Hugh Longbourne Callendar | 30 April 1915 |
| NLB/51/531 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society to Professor Hugh Longbourne Callendar FRS | 19 April 1915 |
| NLB/51/576 | Copy letter from Arthur Schuster, Secretary of the Royal Society to Professor Hugh Longbourne Callendar FRS | 30 April 1915 |
| NLB/51/58 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society to Professor Hugh Longbourne Callendar FRS | 1 December 1914 |
| NLB/53/388 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 25 July 1916 |
| RR/16/77 | Referee's report by Hugh Longbourne Callendar, on a paper 'The measurement of the pressure coefficient of Oxygen' by W Makower and Henry R Noble | August 1903 |
| NLB/52/536 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor Hugh Longbourne Callendar, FRS | 10 January 1916 |
| RR/17/75 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the inversion points for a fluid passing through a porous plug, and their use in testing proposed equations of state' by Alfred William Porter | 10 February 1906 |
| RR/15/39 | Referee's report by Hugh Longbourne Callendar, on a paper 'The evolution of the colour sense' by Frederick Edridge-Green | 14 November 1900 |
| NLB/52/678 | Copy letter from [Robert William Frederick Harrison, Assistant Secretary of the Royal Society]; to Professor Hugh Longbourne Callendar, Chairman of the Physics and Chemistry Committee and FRS | 11 February 1916 |
| RR/18/19 | Referee's report by Charles Vernon Boys, on a paper 'On the absolute expansion of mercury' by Hugh Longbourne Callendar and Herbert Moss | December 1910 |
| NLB/53/249 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 14 June 1916 |
| NLB/52/695 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor Hugh Longbourne Callendar, Chairman of the Physics and Chemistry Committee and FRS | 15 February 1916 |
| RR/17/249 | Referee's report by Hugh Longbourne Callendar, on a paper 'Contributions to the osmotic theory of solution' by Randal Thomas Mowbray Berkeley and C V Burton | 5 December 1908 |
| NLB/58/212 | Copy letter from Edwin Deller, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, FRS | 27 March 1920 |
| RR/27/46 | Referee's report by Hugh Longbourne Callendar, on a paper 'The vapour pressure of lead - I' by A C Egerton | February 1923 |
| RR/18/112 | Referee's report by Arthur Schuster, on a paper 'On the variation of the specific heat of water, with experiments by a new method' by Hugh Lonbourne Callendar | December 1911 |
| NLB/62/562 | Copy letter from James Hopwood Jeans, Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, FRS | 10 March 1922 |
| NLB/54/92 | Copy letter from [Robert William Frederick Harrison, Assistant Secretary of the Royal Society]; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 6 February 1917 |
| RR/27/48 | Referee's report by Hugh Longbourne Callendar, on a paper 'Separation of isotopes of zinc' by A C Egerton and W B Lee | February 1923 |
| NLB/54/146 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 17 February 1917 |
| NLB/54/296 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 26 March 1917 |
| NLB/54/282 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 21 March 1917 |
| NLB/54/313 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 30 March 1917 |
| NLB/54/249 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 16 March 1917 |
| NLB/54/767 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Logbourne] Callendar, Chairman of the Mathematics Committee and FRS | 14 September 1917 |
| RR/22/59 | Referee's report by Hugh Longbourne Callendar, on a paper 'The thermal conductivity of air' by E O Hercus and Thomas Howell Laby | June 1915 |
| RR/21/29 | Referee's report by Hugh Longbourne Callendar, on a paper 'The osmotic data in relation to progressive hydration' by William Robert Bousfield | [July 1914] |
| RR/22/58 | Referee's report by Hugh Longbourne Callendar, on a paper 'An application of the principle of dynamical similitude to molecular physics' by William Bate Hardy | September 1915 |
| RR/27/53 | Referee's report by Hugh Longbourne Callendar, on a paper 'Some moisture relations of colloids - I. A comparative study of the rates of evaporation of water from wool, sand and clay' by E A Fisher | December 1922 |
| RR/22/27 | Referee's report by Alfred Harker, on a paper 'On the specific heat of steam at atmospheric pressure between 104°C and 115°C' by J H Brinkworth and Hugh Longbourne Callendar | May 1915 |
| RR/24/21 | Referee's report by Hugh Longbourne Callendar, on a paper 'The specific heat of aqueous solutions, with special reference to sodium and potassium chlorides' by William Robert Bousfield and C Elspeth Bousfield | [June 1917] |
| NLB/43 | New Letter Book volume 43, copy letters sent from Royal Society administration | 20 October 1910-12 April 1911 |
| NLB/54/533 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 11 June 1917 |
| RR/27/47 | Referee's report by Hugh Longbourne Callendar, on a paper 'Some density determinations' by A C Egerton and W B Lee | February 1923 |
| RR/23/96 | Referee's report by Hugh Longbourne Callendar, on a paper 'A determination of the heat of vaporisation of water at 100°C. and one atmosphere pressure in terms of the mean calorie' by T Carlton Sutton | August 1916 |
| RR/23/57 | Referee's report by Hugh Longbourne Callendar, on a paper 'The use of highly attenuated wires for platinum thermometers' by [John Job] Manley | December 1916 |
| NLB/54/671 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 26 July 1917 |
| NLB/54/756 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Mathematics Committee and FRS | 12 September 1917 |
| NLB/54/646 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 12 July 1917 |
| RR/26/149 | Referee's report by Hugh Longbourne Callendar, on a paper 'The energy in air, steam and carbon dioxide from 100C to 2000C' by W D Womersley | [October 1921] |
| NLB/56/19 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 5 November 1918 |
| NLB/53/52 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, FRS | 27 March 1916 |
| RR/28/2 | Referee's report by Hugh Longbourne Callendar, on a paper 'Heat of crystallisation of quartz' by Rames Chandra Ray | [May 1922] |
| NLB/56/122 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 27 November 1918 |
| RR/25/17 | Referee's report by Hugh Longbourne Callendar, on a paper 'The extension of gas laws to liquids' by John Scott Haldane | [May 1918] |
| NLB/56/155 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 3 December 1918 |
| NLB/53/193 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 23 May 1916 |
| NLB/53/368 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 22 July 1916 |
| NLB/53/182 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 19 May 1916 |
| NLB/53/267 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 21 June 1916 |
| RR/18/138 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the specific heats at high temperature of the latest heats of metals' by H C Greenwood | November 1911 |
| RR/20/35 | Referee's report by Hugh Longbourne Callendar, on a paper 'The boiling-point of sulphur on the thermodynamic scale' by N Eumorfopoulos | January 1914 |
| NLB/56/593 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, FRS | 24 March 1919 |
| RR/9/329 | Referee's report by James Dewar, on a paper 'On the practical measurements of temperature. Experiments made at the Cavendish Laboratory, Cambridge' by Hugh Longbourne Callendar | 17 October 1886 |
| RR/18/133 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the calorimetry of gases: with special reference to gases of low heating value' by W E Fisher | August 1911 |
| NLB/64/683 | Copy letter from James Hopwood Jeans, Secretary of the Royal Society; to [Robert John Strutt] Lord Rayleigh | 2 June 1923 |
| NLB/55/148 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 20 December 1917 |
| NLB/53/652 | Copy letter from [Robert William Frederick Harrison], Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Society and FRS | 20 November 1916 |
| RR/35/15 | Referee's report by Hugh Longbourne Callendar, on a paper 'The specific heats of ferromagnetic substances' by Leslie Fleetwood Bates | November 1927 |
| RR/34/27 | Referee's report by Hugh Longbourne Callendar, on a paper 'Some observations on the Barnes Thermite ice system' by H W Johnston | [December 1926] |
| RR/17/304 | Referee's report by Hugh Longbourne Callendar, on a paper 'The rate of heat transfer between fluids and metal surfaces' by H P Jordan | December 1908 |
| RR/18/120 | Referee's report by Hugh Longbourne Callendar, on a paper 'Radiation in explosions of coal-gas and air' by W T David | May 1911 |
| NLB/28 | New Letter Book volume 28, copy letters sent from Royal Society administration | 17 December 1903-13 June 1904 |
| NLB/55/299 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 18 February 1918 |
| NLB/55/149 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 20 December 1917 |
| NLB/55/47 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 15 November 1917 |
| NLB/19/279 | Copy letter from Robert William Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 26 July 1899 |
| NLB/55/483 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 24 April 1918 |
| RR/18/43 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the magnetic properties of iron and its alloys in intense field' by Robert Abbott Hadfield and Bertram Hopkinson | June 1910 |
| RR/40/87 | Referee's report by Hugh Longbourne Callendar, on a paper 'A new form of calorimeter suitable for determining heats of solutions, with an application to worked and annealed metals' by C J Smith | September 1929 |
| NLB/59/86 | Copy letter from [Maud K. Jukes, Clerk of the Royal Society]; to Professor [Hugh Longbourne] Callendar, FRS | 16 July 1920 |
| MS/928/6/2/14 | Letter from Hugh Longbourne Callendar, Imperial College of Science and Technology, South Kensington, London, to Charles Vernon Boys | 6 October 1926 |
| RR/14/126 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the oxidation of carbon at ordinary temperature by means of atmospheric oxygen with the production of electrical energy' by Willard E Case | 30 May 1899 |
| RR/24/32 | Referee's report by Hugh Longbourne Callendar, on a paper 'The deviation of certain gases from Boyle's Law at high temperatures' by C Cochrane | [June 1917] |
| RR/16/332 | Referee's report by Hugh Longbourne Callendar, on a paper 'Effects of temperature & pressure on the thermal conductivities of solids. Part I. The effect of temperature on the thermal conductivities of some electrical insulations' by Charles Herbert Lees | 12 December 1904 |
| RR/39/113 | Referee's report by Hugh Longbourne Callendar, on a paper 'The melting point of palladium' by F H Schofield | [July 1929] |
| RR/15/372 | Referee's report by Hugh Longbourne Callendar, on the Bakerian Lecture 'The law of the pressure of gases between 75 and 150 millimeters of mercury' by John William Strutt, Lord Rayleigh | February 1902 |
| RR/20/157 | Referee's report by Hugh Longbourne Callendar, on a paper 'On negative adsorption' by A M Williams | 20 November 1913 |
| RR/23/3 | Referee's report by Hugh Longbourne Callendar, on a paper 'Further determinations of direct osmotic pressures' by the Earl of Berkely and E G J Huntley | June 1916 |
| RR/14/131 | Referee's report by Hugh Longbourne Callendar, on a paper 'Investigations on platinum thermometry at Kew Observatory' by Charles Chree | nd [January 1900] |
| RR/17/8 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the osmotic pressures of some concentrated aqueous solutions' by Randal Thomas Mowbray Rawdon Berkeley and E G J Hartley | [June 1906] |
| RR/24/46 | Referee's report by Hugh Longbourne Callendar, on a paper 'The discharge of gases under high pressures' by L Hartshorn | [October 1917] |
| RR/14/278 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the electrical conductivity of flames containing salt vapours' by Harold Albert Wilson | nd [March 1899] |
| RR/37/159 | Third referee's report by Hugh Longbourne Callendar, on a paper 'The effect of temperature on the viscosity of air' by W G Shilling and A E Laxton | [1929] |
| RR/22/26 | Referee's report by Arthur Schuster, on a paper 'On the specific heat of steam at atmospheric pressure between 104°C and 115°C' by J H Brinkworth and Hugh Longbourne Callendar | 1915 |
| NLB/19/311 | Copy letter from an unknown correspondent, to Professor George Carey Foster, Fellow of the Royal Society | 1 August 1899 |
| RR/14/262 | Referee's report by Hugh Longbourne Callendar, on a paper 'The thermal expansion of pure nickel and cobalt' by Alfred Edwin Howard Tutton | [May 1899] |
| RR/18/107 | Referee's report by Hugh Longbourne Callendar, on a paper 'The specific heat of water and the mechanical equivalent of the calorie at temperatures from 0° C. to 80° C' by William Robert Bousfield and W Eric Bousfield | January 1911 |
| NLB/54/426 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 11 May 1917 |
| NLB/55/839 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 14 October 1918 |
| NLB/55/635 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to [Professor Hugh Longbourne] Callendar, FRS | 05 July 1918 |
| NLB/55/752 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to [Professor Hugh Longbourne] Callendar, FRS | 28 August 1918 |
| NLB/62/572 | Copy letter from James Hopwood Jeans, Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, FRS | 15 March 1922 |
| RR/18/49 | Referee's report by Hugh Longbourne Callendar, on a paper 'On radiation in a gaseous explosion' by Bertram Hopkinson | May 1910 |
| NLB/64/287 | Copy letter from James Hopwood Jeans, Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, FRS | 7 March 1923 |
| NLB/62 | New Letter Book volume 62, copy letters sent from Royal Society administration | 11 November 1921-10 June 1922 |
| RR/33/18 | Referee's report by Hugh Longbourne Callendar, on a paper 'Some physical properties of lcebergs and a method for their destruction' by Howard Turner Barnes | December 1926 |
| RR/39/116 | Referee's report by Hugh Longbourne Callendar, on a paper 'The ageing of standard cells; increased accuracy in their use; and international comparisons' by A Norman Shaw, H E Reilley and R J Clark | [April 1929] |
| RR/34/110 | Referee's report by Hugh Longbourne Callendar, on a paper 'The temperature coefficient of the molecular heats of steam' by W G Shilling | [August 1926] |
| NLB/66/422 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; [Robert John Strutt] Lord Rayleigh, FRS | 6 May 1924 |
| NLB/71/198 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to the Editor, the Encyclopedia Britannica, 80 Regent Street, W.1 | 8 February 1928 |
| NLB/71/731 | Copy letter from James Hopwood Jeans, Secretary of the Royal Society; to Prof. [Hugh Longbourne] Callendar, FRS | 16 October 1928 |
| NLB/71/802 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Prof. [Hugh Longbourne] Callendar, FRS | 5 November 1928 |
| NLB/72/642 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Professor [Samuel Walter Johnson] Smith, FRS | 7 February 1930 |
| NLB/73/53 | Copy letter from Francis Alexander Towle, Assistant Secretary of the Royal Society; to Prof. [Samuel Walter Johnson] Smith, FRS | 7 November 1930 |
| NLB/40/363 | Copy letter from Joseph Larmor to [Hugh Longbourne] Callendar | Undated |
| NLB/1/420 | Copy letter from Herbert Rix, to Hugh Longbourne Callendar | 7 March 1887 |
| NLB/33 | New Letter Book volume 33, copy letters sent from Royal Society administration | 13 June 1906-15 November 1906 |
| NLB/42 | New Letter Book volume 42, copy letters sent from Royal Society administration | 4 March 1910-19 October 1910 |
| RR/15/165 | Referee's report by Herbert McLeod, on a paper 'Continuous electrical calorimetry' by Hugh Longbourne Callendar | January 1901 |
| NLB/45 | New Letter Book volume 45, copy letters sent from Royal Society administration | 5 December 1911-21 May 1912 |
| RR/16/217 | Memoranda from Robert William Frederick Harrison, and reply from Hugh Longbourne Callendar and Joseph Larmor, on a paper 'On the seismic effect of tidal stresses' by Richard Dixon Oldham | 10 May 1904 |
| NLB/20/334 | Copy letter from Arthur William Rucker, to Professor George Carey Foster, Fellow of the Royal Society | 26 March 1900 |
| NLB/21/22 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 17 July 1900 |
| NLB/21/275 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 16 October 1900 |
| NLB/42/10 | Copy letter from Robert William Frederick Harrison to Professor H [Hugh] L [Longbourne] Callendar FRS | 7 March 1909 |
| NLB/28/251 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 4 February 1904 |
| NLB/28/258 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 5 February 1904 |
| NLB/28/738 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics Committee | 10 May 1904 |
| NLB/31/62 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 16 June 1905 |
| NLB/32/70 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 20 December 1905 |
| NLB/33/214 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 17 July 1906 |
| NLB/35/280 | Copy letter from Robert William Frederick Harrison, to Professor Arthur Schuster, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 10 May 1907 |
| NLB/36/632 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society | 22 November 1907 |
| NLB/41/577 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 17 January 1910 |
| RR/18/18 | Referee's report by George Downing Liveing, on a paper 'On the absolute expansion of mercury' by Hugh Longbourne Callendar and Herbert Moss | 10 November 1910 |
| RR/24/19 | Referee's report by Hugh Longbourne Callendar, on a paper 'Note on the specific heat of water' by William Robert Bousfield | [June 1917] |
| NLB/54/225 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 8 March 1917 |
| NLB/54/281 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 21 March 1917 |
| NLB/54/532 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 11 June 1917 |
| RR/35/133 | Referee's report by Hugh Longbourne Callendar, on a paper 'The mechanical equivalent of heat' by Thomas Howell Laby and E O Hercus | February 1927 |
| NLB/53/124 | Copy letter from Robert William Frederick Harrison, Assistant Secretary of the Royal Society; to Professor [Hugh Longbourne] Callendar, Chairman of the Physics and Chemistry Committee and FRS | 2 May 1916 |
| RR/10/330 | Referee's report by Robert Bellamy Clifton, on a paper 'On the determination of the boiling-point of sulphur, and on a method of standardising platinum resistance thermometers by reference to it.—Experiments made at the Cavendish laboratory, Cambridge' by Hugh Longbourne Callendar and Ernest Howard Griffiths | 20 January 1891 |
| RR/15/163 | Referee's report by Ernest Howard Griffiths, on a paper 'Continuous electrical calorimetry' by Hugh Longbourne Callendar | 4 January 1902 |
| NLB/28/70 | Copy letter from Robert William Frederick Harrison, to Dr Joseph Larmor, Fellow of the Royal Society | 5 January 1904 |
| NLB/30/205 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 13 February 1905 |
| NLB/29/325 | Copy letter from Robert William Frederick Harrison, to Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 22 September 1904 |
| NLB/32/879 | Copy letter from Robert William Frederick Harrison, to Professor Hugh Longbourne Callendar, Fellow of the Royal Society, Chairman of the Physics and Chemistry Committee | 11 June 1906 |
| NLB/39/264 | Copy letter from Robert William Frederick Harrison to Dr R [Richard] T [Tetley] Glazebrook, Fellow of the Royal Society | 18 December 1908 |
| NLB/54 | New Letter Book volume 54, copy letters sent from Royal Society administration | 10 January 1917-2 November 1917 |
| NLB/61/336 | Copy letter from James Hopwood Jeans, Secretary of the Royal Society; to Professor [Hugh Callendar] Longbourne, FRS | 21 June 1921 |
| IM/000844 | Foster, George Carey | 2001 |
| NLB/32 | New Letter Book volume 32, copy letters sent from Royal Society administration | 9 December 1905-13 June 1906 |
| NLB/53 | New Letter Book volume 53, copy letters sent from Royal Society administration | 9 March 1916-10 January 1917 |
| NLB/30 | New Letter Book volume 30, copy letters sent from Royal Society administration | 14 January 1905-6 June 1905 |
| RR/15/155 | Referee's report by Hugh Longbourne Callendar, on a paper 'A determination by a thermal method of the variation of the critical velocity of water with temperature' by Howard Turner Barnes and Ernest George Coker | 28 October 1901 |
| RR/34/40 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the determination of the specific heats of gases at constant pressure' by Charles Herbert Lees | [May 1926] |
| RR/28/67 | Referee's report by Hugh Longbourne Callendar, on a paper 'Vapour pressure and density of sodium chloride solutions' by William Robert Bousfield and C Elspeth Bousfield | 12 March 1923 |
| RR/37/158 | Second referee's report by Hugh Longbourne Callendar, on a paper 'The effect of temperature on the viscosity of air' by W G Shilling and A E Laxton | 31 December 1928 |
| RR/17/430 | Referee's report by Hugh Longbourne Callendar, on a paper 'The porpous plug experiment' by W A D Rudge | November 1909 |
| AP/78/5 | Unpublished paper, 'The specific heats of air and carbon dioxide. Details of the method of calibration of the potentiometer, with record of data' by W F G [William Francis Gray] Swann | 1908 |
| RR/14/94 | Referee's report by Hugh Longbourne Callendar, on a paper 'The electrical conductivity and luminosity of flames containing vaporised salts' by Arthur Smithells, Harry Medforth Dawson and Harold Albert Wilson | 24 November 1898 |
| RR/15/106 | Referee's report by Hugh Longbourne Callendar, on a paper 'Underground temperature at Oxford in the year 1899 as determined by five platinum resistance thermometers' by Arthur Alcock Rambaut | June 1900 |
| RR/16/196 | Memoranda from Robert William Frederick Harrison [Assistant Secretary], and reply from Hugh Longbourne Callendar, on a paper 'Two-dimensional problems in magnetic induction, with special reference to flux distribution in toothed-core armatures' by Professor Henry Selby Hele-Shaw, Dr Alfred Hay and Mr P H Powell | 15 March 1904 |
| RR/16/362 | Referee's report by Hugh Longbourne Callendar, on a paper 'The pressure of explosions - experiments on solid & gaseous explosives' by James Ernest Petavel | [c 28 October 1905] |
| MS/603/2/3 | Letter from H L [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, London, to [Joseph] Larmor | 14 January 1909 |
| PP/18/11 | Paper, 'On a compensated air thermometer' by Hugh Longbourne Callendar | 1891 |
| RR/16/231 | Referee's report by Hugh Longbourne Callendar, on a paper 'The construction of some mercury standards of resistance, with a determination of the temperature co-efficient of resistance of mercury' by Frank Edward Smith | March 1904 |
| RR/18/20 | Referee's report by Hugh Longbourne Callendar, on a paper 'Sound vibrations of very high frequency produced by electric sparks' by A Campbell and D W Dye | 10 December 1910 |
| RR/14/176 | Referee's report by Hugh Longbourne Callendar, on a paper 'A comparison of platinum and gas thermometers, including a determination of the boiling-point of sulphur on the nitrogen scale. An account of experiments made in the laboratory of the Bureau International des Poids et Mesures Sèvres' by John Allen Harker and Pierre Chappuis | nd [July 1899] |
| RR/15/20 | Referee's report by Hugh Longbourne Callendar, on a paper 'Some new observations on the static diffusion of gases and liquids and their significance in certain natural processes occurring in plants' by Horace Tabberer Brown and F Escombe | June 1900 |
| RR/10/329 | Referee's report by George Carey Foster, on a paper 'On the determination of the boiling-point of sulphur, and on a method of standardising platinum resistance thermometers by reference to it.—Experiments made at the Cavendish laboratory, Cambridge' by Hugh Longbourne Callendar and Ernest Howard Griffiths | 5 January 1891 |
| RR/13/175 | Referee's report by John William Strutt, Lord Rayleigh, on a paper 'On the variation of the electromotive force of different forms of the Clark standard cell with temperature and with strength of solution' by Hugh Longbourne Callendar and Howard Turner Barnes | 17 March 1897 |
| RR/14/132 | Detailed referee's report by Hugh Longbourne Callendar, on a paper 'Investigations on platinum thermometry at Kew Observatory' by Charles Chree | nd [1900] |
| RR/14/244 | Referee's report by Hugh Longbourne Callendar, on a paper [attributed] 'On the reflection of cathode rays' by Alan Archibald Campbell Swinton | 4 February 1899 |
| RR/17/254 | Referee's report by Hugh Longbourne Callendar, on a paper 'Contributions to the osmotic theory of solution' by Randal Thomas Mowbray Berkeley and C V Burton | 1908 |
| RR/20/76 | Referee's report by Hugh Longbourne Callendar, on a paper 'The thermal properties of carbonic acid low temperatures' by Charles Frewen Jenkin and David Randall Pye | February 1913 |
| RR/21/31 | Referee's report by Hugh Longbourne Callendar, on a paper 'An approximate estimate of the constituents of water' by William Robert Bousfield | [December 1914] |
| RR/21/102 | Referee's report by Hugh Longbourne Callendar, on a paper 'On the convection of heat from small cylinders in a stream of fluid: Determination of the convection constants of small platinum wires with applications to hot-wire anemometry' by Louis Vessot King | [May 1914] |
| RR/24/7 | Referee's report by Hugh Longbourne Callendar, on a paper 'On osmotic pressures derived from vapour-pressure measurements: Aqueous solutions of cane sugar and methyl glucoside' by Randal Thomas Mowbray Rawdon Berkeley, 8th Earl Berkeley, E G J Hartley and C V Burton | [March 1917] |
| RR/27/106 | Referee's report by Hugh Longbourne Callendar, on a paper 'The thermal stresses in solid and in hollow circular cylinders concentrically heated' by Charles Herbert Lees | May 1922 |
| RR/37/157 | Referee's report by Hugh Longbourne Callendar, on a paper 'The effect of temperature on the viscosity of air' by W G Shilling and A E Laxton | [September 1928] |
| RR/38/59 | Referee's report by Hugh Longbourne Callendar, on a paper 'The international temperature scale between 0° and 100° C' by J A Hall | July 1929 |
| RR/39/117 | Second referee's report by Hugh Longbourne Callendar, on a paper 'The ageing of standard cells; increased accuracy in their use; and international comparisons [abstract]' by A Norman Shaw, H E Reilley and R J Clark | [April 1929] |
| RR/16/267 | Referee's report by Hugh Longbourne Callendar, on a paper 'The determination of the osmotic pressure of solutions by the measurement of their vapour pressures' by the Earl of Berkeley and E G J Hartley, and on a paper 'The relation between osmotic pressure & the vapour pressure of a solution' by Will Spens | 17 November 1905 |
| RR/16/353 | Referee's report by Hugh Longbourne Callendar, on a paper 'The determination of the specific heat of superheated steam by throttling & other experiments' by Mr A H Peak | 30 March 1905 |
| MC/14/219 | Letter from Hugh [Longbourne] Callendar, Trinity College, Cambridge, to the Secretary of the Royal Society | 6 June 1887 |
| MC/19/156 | Letter from [Hugh Longbourne] Callendar, 2 Chester Place, Regents Park, to [Robert William Frederick] Harrison | 4 February 1904 |
| MC/14 | Volume 14 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1885-1888 |
| MC/19/157 | Letter from [Hugh Longbourne] Callendar, 2 Chester Place, Regents Park, to [Robert William Frederick] Harrison | 21 March 1904 |
| MC/19/159 | Letter from [Hugh Longbourne] Callendar, Saundersfoot, South Wales, to [Robert William Frederick] Harrison | 16 July 1904 |
| MC/19/163 | Letter from [Hugh Lonbourne] Callendar, Board of Education, South Kensington, London, to [Robert William Frederick] Harrison | 16 November 1904 |
| MC/19/162 | Letter from [Hugh Lonbourne] Callendar, Board of Education, South Kensington, London, to [Joseph] Larmor | 14 November 1904 |
| MC/19/158 | Letter from [Hugh Lonbourne] Callendar, Board of Education, Royal College of Science, London, to [Robert William Frederick] Harrison | 12 May 1904 |
| MC/19/161 | Letter from [Hugh Longbourne] Callendar, 2 Chester Place, Regents Park, to [Robert William Frederick] Harrison | 22 September 1904 |
| MC/23/81 | Letter from [Hugh Longbourne] Callendar , 49 Grange Road, Ealing, London, to [Robert] Harrison, The Royal Society | 24 December 1908 |
| AP/78/5/1 | Unpublished manuscript, 'The specific heats of air and carbon dioxide. Details of the method of calibration of the potentiometer, with record of data' by W F G [William Francis Gray] Swann | 1908 |
| MS/603/2/4 | Letter from H L [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, London, to [Joseph] Larmor | 27 January 1909 |
| MC/17 | Volume 17 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1897-1899 |
| MC/26/45 | Letter from [Hugh Longbourne] Callendar, Imperial College of Science and Technology, Royal College of Science, South Kensington, London, S.W, to [Robert] Harrison, [Royal Society] | 1 June 1911 |
| MC/27/49 | Letter from [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, W, to [Robert] Harrison, [Royal Society] | 11 February 1912 |
| MC/27/46 | Letter from [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, W, to [Robert] Harrison, [Royal Society] | 20 January 1912 |
| MC/28/36 | Letter from [Hugh Longbourne] Callendar, to [Robert] Harrison, [Royal Society] | 5 December 1913 |
| MC/21/94 | Letter from [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, to the President and Council of the Royal Society | 2 November 1906 |
| MC/21/92 | Letter from [Hugh Longbourne] Callendar, Board of Education, South Kensington, London, to [Robert William Frederick] Harrison | 7 February 1906 |
| MC/21/93 | Letter from [Hugh Longbourne] Callendar, Board of Education, Royal College of Science, South Kensington, to [Robert William Frederick] Harrison | 26 May 1906 |
| MC/19 | Volume 19 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1904 |
| MC/22/45 | Letter from [Hugh Longbourne] Callendar, Board of Education, Royal College of Science, London, South Kensington, to [Robert William Frederick] Harrison | 19 November 1907 |
| MC/32/40 | Letter from [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, W, to [Robert] Harrison, [Royal Society] | 13 May 1917 |
| MC/32/39 | Letter from [Hugh Longbourne] Callendar, Imperial College of Science and Technology (Royal College of Science), South Kensington, London, S.W, to [Robert] Harrison, [Royal Society] | 12 March 1917 |
| MC/22/44 | Letter from [Hugh Longbourne] Callendar, Board of Education, Royal College of Science, London, South Kensington, to [Robert William Frederick] Harrison | 28 October 1907 |
| MC/33/19 | Letter from [Hugh Longbourne] Callendar, Imperial College of Science and Technology (Royal College of Science), South Kensington, London, S.W.7., to [Robert] Harrison, [Royal Society] | 9 December 1918 |
| MC/38/7 | Letter from [Hugh Longbourne] Callendar, Imperial College of Science and Technology (Royal College of Science), South Kensington, London, to [Francis Alexander] Towle | 21 October 1924 |
| MC/38 | Volume 38 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1924 |
| MC/27/47 | Letter from [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, W, to [Robert] Harrison, [Royal Society] | 31 January 1912 |
| MC/22 | Volume 22 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1907 |
| MC/21 | Volume 21 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1906 |
| MC/23/18 | Letter from [Edward] Frankland Armstrong, 98 London Road, Reading, to [Robert] Harrison, Assistant Secretary, The Royal Society | 18 February 1908 |
| MC/27/48 | Letter from [Hugh Longbourne] Callendar, Imperial College of Science and Technology, Royal College of Science, South Kensington, London, S.W | 6 February 1912 |
| MC/23 | Volume 23 of miscellaneous correspondence regarding business matters, sent to the Royal Society | 1908 |
| MS/603/2/2 | Letter from H L [Hugh Longbourne] Callendar, Royal College of Science, South Kensington, London, to [Joseph] Larmor | 26 February 1908 |
| MS/603/2/5 | Letter from H L [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, London, to [Joseph] Larmor | 10 March 1910 |
| MS/603/2/1 | Letter from H L [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, London, to [Joseph] Larmor | 19 February 1908 |
| MS/603/2/6 | Letter from H L [Hugh Longbourne] Callendar, 49 Grange Road, Ealing, London, to Joseph [Larmor] | 8 November 1911 |
| MS/603/2/7 | Letter from H L [Hugh Longbourne] Callendar, Imperial College of Science and Technology, South Kensington, London, to [Joseph] Larmor | 15 May 1914 |