Having communicated with General Oetzel, the chief of the military telegraphic service, he was invited to assist in the substitution of electric for optical telegraphs. He gained the confidence of the general and of his son-in-law, Prof. Dove, and was commissioned to carry out his own plans. The lines were to be put underground, and there was difficulty about finding satisfactory insulating material. Wilhelm Siemens had sent him some specimens of gutta percha from London as a curiosity. It was found eminently adapted to the purpose of an insulator. With a press supplied by Halske, the wires were successfully covered, and the lines were established with Siemens's instruments. In October, 1847, the firm of Siemens and Halske was formed, which, beginning in a rear building with a modest capital, was destined to ramify till it had branches in several of the capitals of Europe, and became prominent in the construction of Continental telegraphs and the world's cable lines.
The revolutionary movements of 1848 brought the extension of telegraphic enterprises to a temporary halt. The Siemens-Halske establishment, nevertheless, went on with its work, though it had no orders. In a short time Siemens was commissioned to lay submarine electric batteries in the harbor of Kiel for protection against an apprehended attack by Danish vessels. Having assured the perfect working of his mines from the shore, he collected a band of volunteers in the city and surprised the post of Friedrichsort, at the entrance to the harbor, under the protection of which, it being held by the Danes, the Danish fleet might have approached alarmingly near to Kiel without being molested. As commandant of Friedrichsort, he built the fortifications for the protection of the harbor of Eckernförde, which became very famous the next year in connection with the rout of the Danish squadron.
Siemens was next commissioned to lay an underground telegraph from Berlin to Frankfort-on-the-Main where the German National Assembly met. The transmission of the result of an election in the winter of 1879 to Berlin, within the hour, gave the line great repute, and Siemens was employed to construct another line from Berlin to Cologne and Verviers, on the Prussian frontier. In this enterprise he had the assistance of William Meyer, a man skilled in organization. Many difficulties incident to the imperfections of an art still in a crude condition are described as having been encountered in executing these works. The constructors were sorely embarrassed, in crossing the Elbe and the Rhine, to find means for protecting the wires against dragging by ships' anchors. The wire across the Rhine was inclosed in a wrought-iron tube so well that, when it was taken up several years afterward, a number of anchors were found hanging from
