The working of these instruments requires, as may be supposed, undivided attention, and accordingly there is very properly affixed to the wall of the chamber in which they stand the following notice, which we implicitly obeyed:-- “_Do not interrupt the clerks while engaged at the instruments._” As the Vicar of Wakefield’s most important movements in life were “from the blue bed to the brown one,” so we must now request our readers to migrate with us from the attics of the Electric Telegraph Office to a low, dark, groined, 5th-of-November-looking cellar, thirty-two feet long by five in width, containing three shelves, on which are to be seen, lying in double rows, thirty-four galvanic batteries, or, to speak in more homely terms, small open troughs, five inches broad, and either thirty-two inches or twenty inches in length. The largest, weighing, when charged, 60 lbs., are called “twenty-fours,” because they contain that number of pairs of plates of copper and zinc separated by a little sand, the whole being then brought into galvanic action by being sluiced with sulphuric acid and water mixed in the proportions of one of the former to twelve of the latter. The smallest, called “twelves,” contain only that number of pairs of plates. Of these batteries it requires from four to six of the largest to be applied to one instrument to blow a message from London to Edinburgh. A single “twelve,” applied to each instrument, will project intelligence to a range of four or five miles. These batteries are connected with the eight instruments in the attics by small copper wires, which, to prevent confusion of action from contact one with another, are covered with cotton thread, saturated with a mixture of tar, rosin, and grease. With this simple precaution, nine wires, insulated from each other, are packed in a half-inch leaden tube, in which they again descend from the instruments to the cellar region. Four or five of these pipes are there packed into an iron pipe three inches in diameter, which conducts them under the foot pavement of the streets to the termini of the arterial rail-roads, alongside of which, and in the open air, a series of lines resembling those on which music is written, composed of galvanised iron, stout enough to bear tension, and suspended by posts, have, as is well known, been constructed. Along the street pavement, at every quarter of a mile, there are cast-iron “_testing-posts_” to enable the Company’s servants to examine all these wires in order to detect and remove any that require to be renewed.