ſervations opened a new field for inveſtigation, upon which electricians entered with avidity; and their labours have added much to the ſtock of our knowledge.
In September 1752, Franklin entered upon a courſe of experiments, to determine the ſtate of electricity in the clouds. From a number of experiments he formed this concluſion: "that the clouds of a thunder-guſt are moſt commonly in a negative ſtate of electricity, but ſometimes in a poſitive ſtate;" and from this it follows, as a neceſſary conſequence, "that, for the moſt part, in thunder-ſtrokes, it is the earth that ſtrikes into the clouds, and not the clouds that ſtrike into the earth." The letter containing theſe obſervations is dated in September 1753; and yet the diſcovery of aſcending thunder has been ſaid to be of a modern date, and has been attributed to the Abbé Bertholon, who published his memoir, on the ſubject in 1776.
Franklin's letters have been tranſlated into moſt of the European languages, and into Latin. In proportion as they have become known, his principles have been adopted. Some oppoſition was made to his theories, particularly by the Abbé Nollet, who was, however, but feebly ſupported, whilſt the firſt philoſophers of Europe ſtepped forth in defence of Franklin's principles; amongſt whom D'Alibard and Beccaria were the moſt diſtinguiſhed. The oppoſition has gradually ceaſed, and the Franklinian ſyſtem is now univerſally adopted, where ſcience flouriſhes.
The important practical uſe which Franklin made of his diſcoveries, the ſecuring of houſes from injury by lightning, has been already mentioned. Pointed conductors are now very common in America; but prejudice has hitherto pre-
