Georges CLAUDE (1870-1960), French physicist. Important file of 13 manuscripts, working notes and letters relating to the research he carried out from 1928 to 1935 on the thermal energy of the seas, in Cuba, Brazil and in the laboratory. A fine collection of his research on the boiling of water, hydraulic machines, ultrasound, etc. - 4 autograph pieces containing working notes on Cuban hydraulic machines with drawings and calculations. In-8 oblong or in-12 oblong. - Draft letter to Carlos Rojes, Cuban Minister of War and Navy (Havana, 30 October 1928. 1 p. in-4. Requests permission to consult the hydraulic maps in his Ministry containing the latest results of research carried out by the American army on the coast of Cuba. - Note on solar studies, studies on water at various stages of boiling, on the rates of heating and warming of water used for research into the extraction of energy from the seas. 4 pp. large in-4. Pencil on paper. - Preparatory note to present the results of his research with Paul Boucherot [(1869-1943), a physicist specialising in the transient phenomena of short-circuiting and coupling alternators to their magnetic leaks] relating the particularities they were able to find in their research to extract energy from the seas. 1 October 1928. 1 page in-8. - Research note on ultrasound. 25 October 1929. 1 page in-8. - 3 letters concerning a lecture to be given by Georges Claude in Rouen in 1931 to present to the Société Industrielle the results of his experiments in Cuba. The first is a draft letter from Claude to Camille Lion (1 p. ¼ in-8 on his letterhead). The other two are typed letters signed by Camille Lion, addressed to M. Cauderay. 2 pp. large in-4 on his letterhead. - Note indicating that he is returning to Cuba around 25 September, etc. 11 August 1928. 1 p. large in-4. - Note on André Marty. 31 October 1929. 1 p. in-8. Letterhead. Attached is a reprint-à-part containing an extract from his report to the Académie des Sciences on research into the thermal energy of the seas, with remarks by Arsène d'Arsonval. Session of 18 March 1935. 7 pp. in-4. [Georges Claude is the author of a large number of works with considerable practical consequences. In 1897, he showed that acetylene could be safely transported by dissolving it in acetone, and this process was immediately adopted by industry. In 1902, he perfected an industrial process for liquefying air by expansion with external work; he used liquid air to prepare oxygen and nitrogen. In 1909, he experimented with liquid oxygen explosives, which were used industrially from 1912. In 1910, he showed how neon tubes could be used for lighting. He discovered the multiplication of the absorbent power of porous coal at low temperatures, a property exploited to obtain high voids. In 1917, he invented a process for synthesising ammonia using a pressure of a thousand atmospheres. From 1926 onwards, he was concerned with finding new sources of energy; he carried out tests on the use of the temperature difference between deep marine waters and the surface layers. He was elected a member of the Académie des Sciences in 1924 (Dictionnaire des inventeurs et inventions, Thomas de Galiana and Michel Rival, p. 247).