The Theory and Practice of Aerostation. [Bound together with] Description, and Use, of the Telescopical Mother-of-Pearl Micrometer. de Cavallo, Tiberius - 1785. And London: printed for th

London: printed for the author and sold by C. Dilly, P. Elmsly, and J. Stockdale,, 1785. And London: printed for the author and sold by C. Dilly, 1793. Octavo (208 x 130 mm). Contemporary tree calf handsomely rebacked to style, spine gilt in compartments, red morocco label. 8 page index and author's ad. The Micrometer being 41 pages with two leaves of preliminaries. 2 engraved folding plates, extra-illustrated with 3 plates from an unknown edition of Faujas de Saint-Fond's book on the Montgolfier brothers, Description des Expériences de la Machine Aérostatique. Armorial bookplate. Professionally rebacked and with the corners and edges of the boards restored, occasional light spotting to the edges of the textblock and the contents, a little toning and offsetting of the plates, mostly affecting the plates introduced from the Saint-Fond, but generally clean and fresh. A very good copy. First edition of the first English-language scientific treatise on ballooning. This copy includes Cavallo's uncommon 1793 treatise on the mother-of-pearl micrometer he invented, and is extra-illustrated with three plates from an unknown edition of Saint-Fond's book on the Montgolfier brothers, Description des Expériences de la Machine Aérostatique (first published 1783-84). In his early twenties Tiberius Cavallo (1749-1809) moved from Italy to London, where "he moved easily in cultivated circles and developed an interest in electrical experiments, in particular on atmospheric electricity. His experimental skill and inventiveness brought him quickly to the notice of some of the leading natural philosophers of the day. He designed an ingenious electrometer for detecting and measuring the smallest quantity of electricity in the atmosphere, and in 1777 he published A Complete Treatise on Electricity in Theory and Practice with Original Experiments... The work was a compendium of contemporary understanding of electricity, and in it Cavallo emphasized the importance of experiments for the advancement of natural knowledge and identified possible directions for further investigation, both practical and theoretical. The Treatise was well received, and it earned him a high reputation within the Royal Society of London, of which he was elected a fellow on 9 December 1779" (ODNB). Cavallo was a talented experimentalist and inventor; he undertook serious investigations into topics such as the medical uses of electricity and the physical properties of air and other gases. He invented and improved on a large number of instruments, and also acted as an international agent for London instrument makers. Serving as the Bakerian Lecturer of the Royal Society ibetween 1782 and 1792, he was a skilled science communicator whose books and lectures were well-received by the public as well as his peers. The History and Practice of Aerostation contains a detailed history of ballooning and aerostatic experiments, including early unmanned flights, the work of the Montgolfier brothers, Pilatre de Rozier, and a large number of other amateur and professional experimenters. The second half of the volume covers the theory of ballooning with sections on the nature of air, the construction of balloons, the mechanisms for sending them aloft and bringing them back to Earth, scientific experiments and observations that can be made during a voyage, and a short essay on the uses to which the new invention may be put in the future. "It can hardly be expected that, in the present state of the subject, all, or even a few, of the uses, to which the aerostatic machines may be applied, should be precisely known, since the decisive proof of experience has not yet been sufficiently shewn" (p. 320). The second text bound into this volume describes one of Cavallo's inventions, a "simple and valuable" micrometer, for making small measurements while using a microscope or telescope. "The Mother-of-pearl micrometer is a very simple, and at the same time, a very accurate instrument of the kind. It consists of a small semitransparent scale or slip of Mother-of-pearl, about the 20th part of an inch broad, and of the thickness of common writing paper, divided into a number of equal parts by parallel lines, every fifth and tenth of which is a little longer than the rest" (pp. 3-4).