key, a phial was charged, a shock given, and all the experiments made which are usually performed with electricity.' And thus the identity of lightning and electricity was proved. ... Franklin's proposition to erect lightning rods which would convey the lightning to the ground, and so protect the buildings to which they were attached, found abundant opponents. ... Nevertheless, public opinion became settled ... that they did protect buildings. ... Then the philosophers raised a new controversy as to whether the conductors should be blunt or pointed; Franklin, Cavendish, and Watson advocating points, and Wilson blunt ends. ... The logic of experiment, however, showed the advantage of pointed conductors; and people persisted then in preferring them, as they have done ever since." {771} _P. Benjamin, The Age of Electricity, chapter 3._ ELECTRICITY: A. D. 1753-1820. The beginnings of the Electric Telegraph. "The first actual suggestion of an electric telegraph was made in an anonymous letter published in the Scots Magazine at Edinburgh, February 17th, 1753. The letter is initialed 'C. M.,' and many attempts have been made to discover the author's identity. ... The suggestions made in this letter were that a set of twenty-six wires should be stretched upon insulated supports between the two places which it was desired to put in connection, and at each end of every wire a metallic ball was to be suspended, having under it a letter of the alphabet inscribed upon a piece of paper. ... The message was to be read off at the receiving station by observing the letters which were successively attracted by their corresponding balls, as soon as the wires attached to the latter received a charge from the distant conductor. In 1787 Monsieur Lomond, of Paris, made the very important step of reducing the twenty-six wires to one, and indicating the different letters by various combinations of simple movements of an indicator, consisting of a pith-ball suspended by means of a thread from a conductor in contact with the wire. ... In the year 1790 Chappe, the inventor of the semaphore, or optico-mechanical telegraph, which was in practical use previous to the introduction of the electric telegraph, devised a means of communication, consisting of two clocks regulated so that the second hands moved in unison, and pointed at the same instant to the same figures. ... In the early form of the apparatus, the exact moment at which the observer at the receiving station should read off the figure to which the hand pointed was indicated by means of a sound signal produced by the primitive method of striking a copper stew pan, but the inventor soon adopted the plan of giving electrical signals instead of sound signals. ... In 1795 Don Francisco Salva ... suggested ... that instead