That communications by this means may often be of great importance, is evident, from many newspaper paragraphs. The following appeared in the early part of 1847: “On Friday evening the following message was received at the Chesterfield station: ‘Tell Derby, a Mr. H. has escaped from the York Asylum, and is supposed to have fire-arms about his person. Search all the trains from York. He is tall, has a crooked nose, and has a green coat with pockets at the side. Tell the police to look out.’ To this message another succeeded from Leeds: ‘He is caught at Leeds; they have him quite secure.’” An establishment has lately been opened near the Bank of England, in which telegraphic intelligence may be despatched, or received, in all the principal towns of our country. The difficulties which have existed in reference to sub-marine telegraphs appear to have been overcome; for the time occupied from the commencement of carrying the telegraph across Portsmouth harbour, and transmitting signals, does not occupy a quarter-of-an-hour. The telegraph, which has the appearance of an ordinary rope, is coiled into one of the dockyard boats, one end of it being made fast on shore; and, as the boat is pulled across, the telegraphic rope is gradually paid out over the stern, its superior gravity causing it to sink to the bottom immediately. The telegraph consists of but this line; and, unlike those along the various railways, requires no return wires to perfect the circuit. The electric fluid is transmitted from the batteries in the dockyard, through the submersed insulated wire to the opposite shore; the fluid returning to the negative pole through the water without the aid of any metallic conductor, except a short piece of wire thrown over the dockyard parapet into the water, and connecting it with the batteries. The fact of the water acting as a ready return conductor, is established beyond question. In 1842, Mr. Snow Harris, when proving the efficiency of his lightning-conductors in his experiments from this dockyard to the Orestes, exemplified that water would serve to complete the electric circuit. On that occasion, the distance traversed by the return current through the water was but trifling compared with the space accomplished in the present instance. The batteries used are Smee’s; and a very delicate and accurate galvanic detector, invented by Mr. Hay, the chemical lecturer of the dockyard, has also been brought into requisition. Independent of the simplicity of this sub-marine telegraph, it has an advantage which even the telegraphs on land do not possess--in the event of accident, it can be replaced in ten minutes.