the large-surface battery, be put at the receiving station; and the current coming over the line be used simply to make and break the circuit of that local battery. ... This is the principle of the telegraphic 'relay.' In 1835 Henry worked a telegraph-line in that way at Princeton. And thus the electro-magnetic telegraph was completely invented and demonstrated. There was nothing left to do, but to put up the posts, string the lines, and attach the instruments." _P. Benjamin, The Age of Electricity, chapter 11._ "At last we leave the territory of theory and experiment and come to that of practice. 'The merit of inventing the modern telegraph, and applying it on a large scale for public use, is, beyond all question, due to Professor Morse of the United States.' So writes Sir David Brewster, and the best authorities on the question substantially agree with him. ... Leaving for future consideration Morse's telegraph, which was not introduced until five years after the time when he was impressed with the notion of its feasibility, we may mention the telegraph of Gauss and Weber of Göttingen. In 1833, they erected a telegraphic wire between the Astronomical and Magnetical Observatory of Göttingen, and the Physical Cabinet of the University, for the purpose of carrying intelligence from the one locality to the other. To these great philosophers, however, rather the theory than the practice of Electric Telegraphy was indebted. Their apparatus was so improved as to be almost a new invention by Steinheil of Munich, who, in 1837 ... succeeded in sending a current from one end to the other of a wire 36,000 feet in length, the action of which caused two needles to vibrate from side to side, and strike a bell at each movement. To Steinheil the honour is due of having discovered the important and extraordinary fact that the earth might be used as a part of the circuit of an electric current. The introduction of the Electric Telegraph into England dates from the same year as that in which Steinheil's experiments took place. William Fothergill Cooke, a gentleman who held a commission in the Indian army, returned from India on leave of absence, and afterwards, because of his bad health, resigned his commission, and went to Heidelberg to study anatomy. In 1836, Professor Mönke, of Heidelberg, exhibited an electro-telegraphic experiment, 'in which electric currents, passing along a conducting wire, conveyed signals to a distant station by the deflexion of a magnetic needle enclosed in Schweigger's galvanometer or multiplier.' ... Cooke was so struck with this experiment, that he immediately resolved to apply it to purposes of higher utility than the illustration of a lecture. ... In a short time he produced two telegraphs of different construction. When his plans were completed, he