Blagden Papers at the Royal Society

Clara Anderson

The personal archive of Sir Charles Blagden FRS, held by the Royal Society, presents a comprehensive portrait of a man of science in Britain in the late eighteenth and early nineteenth centuries. It reveals much about the domestic and international scene in which Blagden worked and the wider social scene in which he moved. At the close of 2006, work was completed on making detailed descriptions of this fascinating collection of correspondence and related manuscripts available on the Society's archive catalogue.1

Sir Charles Blagden (1748–1820) was a physician, a chemist and, from 1784 to 1797, Secretary of the Royal Society. After medical studies at Edinburgh he began his professional career at Gloucester Infirmary. Dissatisfied with his progress there he enlisted as an army doctor and served with the British during the American War of Independence. On his return to England he pursued his interest in physical chemistry. He had been elected a Fellow of the Royal Society in 1772, proposed by his friend Joseph Banks, and from 1782 to 1789 was Henry Cavendish's assistant. Blagden's own chemical researches led to the conclusion that salt lowers the freezing point of water in a simple inverse ratio, now known as ‘Blagden's law’. He also examined the human ability to withstand high temperatures.2

Blagden travelled widely in Europe and had particularly close professional and personal links with French scientists. His travels, together with his role as Secretary of the Society, enabled him to establish a network of prominent contacts. As a result he became embroiled in the prolonged controversy between Cavendish, Watt and Lavoisier over who had priority in discovering the composition of water. Blagden admitted responsibility for conveying, quite well-meaningly, word of the experiments and conclusions of both Cavendish and Watt to Lavoisier.

The Blagden Papers were purchased by the Royal Society in 1947.3 They consist of 41 volumes and 14 boxes in total. There are 6 volumes of letters to Blagden, with drafts of his replies; 1 volume of copy letters to various correspondents; 8 volumes containing Blagden's diary (1771–1820); 15 boxes of notes and personal papers and 26 volumes of printed books and monographs.4 This numerical list of contents suggests, but does no real justice to, the comprehensive coverage of the material.

Blagden's papers contain many items of personal interest: financial papers such as bills and receipts, dating from his student days in Edinburgh through to his gentlemanly expenses on clothing, servants and even some Wedgwood teaware.

As would be expected, there are many items of scientific interest including Blagden's draft of his paper on self-experiments in a heated room and his work to determine the exact specific gravity of spirituous liquors as well as information on the joint trigonometrical survey with France. Contemporary issues such as air balloons, lightning conductors and gunpowder experiments, phlogiston and the development of scientific instruments are documented, as are expeditions to explore Egypt, Malaysia and Australia. Blagden also drafted a Tahitian–English dictionary based on his conversations with Omai, who had returned from the Pacific Ocean with James Cook. Also preserved are accounts of scientific organizations, notably Count Rumford's papers describing the origin of the Royal Institution and information on Blagden's own candidature for the post of Secretary of the Royal Society.

Other topics to arise in the correspondence include health and finance, political news and views, Blagden's brief military career, and news of family and friends, both at home and abroad. Notable correspondents include Sir Joseph Banks, Henry Cavendish, Claude Louis Berthollet, Count Rumford and family, James Munro (fifth President of the United States), Sir Charles Pole and Baron Mulgrave. The financier Henry Hope, one of the men behind the Louisiana Purchase when the United States acquired a vast tract of territory from France, is represented. Blagden corresponded with a number of women, discussing reading materials with Georgiana, Duchess of Devonshire,5 and medical treatments such as green tea with Lady Isabella Hamilton.6 There are also exchanges between Blagden and Mary Berry, a friend of Horace Walpole's. From the correspondence it seems that Blagden attended Walpole on his deathbed.7

Further details of Blagden's life and of those he met are available in his extensive diary, currently described in the catalogue by ranging dates only. This window into science and society at the turn of the eighteenth century requires transcription of his virtually illegible handwriting if it is to be of much use to general researchers. Further work is also needed to describe an additional deposit of papers, received from Blagden's descendants in 2000.8


    1. The catalogue can be accessed at Search the Archive catalogue for ‘Blagden Papers’.

    2. ;

    3. The books from the Blagden collection have been catalogued in the Library catalogue and are to be found under the Classmark ‘Blagden’.

    4. Blagden Letters (Ref: BLA.D.61).

    5. Blagden Letters (Ref: BLA.L.58).

    6. Blagden Letters (Ref: BLA.B.121).

    7. MS/821 Blagden Collection.