Though not fully realized at the time by the capitalists who financed his scheme, by the engineers and electricians who carried it out, or even by statesmen, economists and social reformers, the slender copper cord, buried away from human ken amidst the _débris_ of minute organisms, was destined to effect a revolution in the affairs of men greater than any achieved by the wisdom of sages or the policy of legislators. Owing to the electrostatic capacity of the cable, signaling would have been difficult and unsatisfactory had it not been for the resourcefulness of Prof. Thomson, who devised his reflecting galvanometer to serve as receiving instrument. The principle of the mirror applied in this way was not new, for it had been suggested by Poggendorff and even used by Gauss in connection with very heavy magnets. The magnets used by Thomson, on the other hand, were strips of watch-spring weighing about a grain each, so that even a very weak current coming through the cable would be sufficient to produce strong displacements of the spot of light on the scale. Thomson was clearly the first to insist on small dimensions in magnetic instruments, and to show that reduction in size would be attended with corresponding increase in sensitiveness. The mirror galvanometer, surrounded with a thick iron case to screen it from the magnetic field due to the iron of the ship, the "iron-clad galvanometer" as it was called, was used for the first time on the telegraphic expedition of 1858. The instrument itself, which was fitted up on board the _Niagara_ and which was connected with so many episodes of thrilling interest, was placed by Prof. Thomson in the collection of historical apparatus in the University of Glasgow, where it is at the present day. Beautiful as was the invention of the mirror galvanometer, it gave neither warning of the beginning of a message nor a permanent record of it. Sitting in his dark room, the operator had to be always on the alert for the first swing of the spot of light over the scale. To obviate these drawbacks, Thomson, after some thinking and more talking with his friend White, of Glasgow, finally patented the _siphon-recorder_, in which a glass siphon of capillary dimensions is pulled to the right or left by the action of the current flowing through a light movable coil, and is thus made to register signals in ink on a vertical strip of paper which is kept in uniform motion by a train of clockwork. It is by this simple but very ingenious instrument that messages are received and recorded to-day at all the cable-stations of the world. The inaugural message through the cable came from the Directors of the Atlantic Telegraph Company in Great Britain to the Directors in America, saying: "Europe and America are united by telegraph; glory to God in the highest, on earth peace and good will toward men." The message from Queen Victoria to President Buchanan, consisting of 95 words, took 67 minutes in transmission; it read: