FRANKLIN, Benjamin. Experiments and Observations on Electricity, Made at Philadelphia in America...To Which Are Added, Letters and Papers on Philosophical Subjects. The Whole Corrected, Methodized, Improved, and Now First Collected into One Volume, and Illustrated with Copper Plates. London: Printed for David Henry, and sold by Francis Newbery, 1769. ,iv,,496[i.e. 510, accounting for mispagination, plus four extra pages where the page numbers have been duplicated, i.e. page numbers 112-113 and 416-417 appear twice],pp. including leaf of errata and advertisement "concerning this fourth edition," plus seven engraved plates (two folding). Half title present but misbound (between pp.150 and 151). Quarto. Modern three-quarter calf and marbled boards, spine ruled in gilt, gilt leather label. Title, preface, and errata leaves expertly strengthened along the upper edge and foredge, outer corners of final four index leaves restored (not affecting text in any instances). An occasional small, closed tear in upper margin. Five-digit inked number in margin of preface leaf. Text with light, even tanning, offsetting from the plates. About very good. Untrimmed. "America's first great scientific contribution" - Howes. This is the fourth, first collected, and by far most desirable edition, containing for the first time complete notes on all the experiments, as well as correspondence between Peter Collinson, Franklin, and other collaborators. Franklin began experimenting with electricity as early as 1745, demonstrating the electrical property of lightning and inventing the lightning conductor. This volume includes summaries of his work with Leyden jars, charged clouds, and lightning rods, as well as his famous kite and key experiment. In addition to the electrical experiments it contains the important discovery of the course of storms over North America and other important meteorological observations. The work caused a sensation in the scientific world when first published in 1751, and ranked in the eyes of many of Franklin's contemporaries as far beyond any of his political achievements. Harvard and Yale awarded him honorary degrees in 1753; he received the highest award of the Royal Society, the Copley Medal, the same year; and he was elected to the Society in 1756, the first American to be so honored. This fourth edition.