FRANKLIN, BENJAMIN. Experiments and Observations on Electricity, Made at Philadelphia in America ... To which are added, Letters and Papers on Philosophical Subjects.... London: For F. Newbery, 1774. 4to. v, , 514,  p. 7 engraved plates, several woodcut text illustrations. Lacks half-title. Contemporary marbled paper-covered boards, calf spine, very skillfully rebacked in period style. Later endpapers. Occasional foxing of both text and plates, some offsetting from a few plates, light stains on H3-4 and 2M3-4. Withal a very good copy. The fifth and final edition of the book that PMM calls "the most important scientific book of eighteenth-century America." "English editions one, two, and three had been published carelessly ... he edited the fourth edition in person [and] introduced footnotes ... Other notes corrected faults of early ignorance. In some cases the actual text was revised ... The most outstanding difference ... is of course in content."?I. Bernard Cohen, Benjamin Franklin's Experiments. In addition to the famous kite and key experiment, Franklin's work with Leiden jars, lightning rods, and charged clouds is summarized. The fifth edition is essentially a reprint of the fourth edition with several small corrections. PMM 199 (1st edn.); Wheeler Gift 367b; Ford 307; Howes F320 ("b").