Steinheil suggested the plan of receiving telegraphic signals by means of two bells, one muffled and the other free, to be struck by the needle or needles when deflected by two currents. This plan has been adopted by Sir Charles Bright on the relay system, with a local battery to supply the mechanical power required to strike the bells. This is used at the principal *stationa of the British and Irish Magnetic Tele graph Company. The transmitting instrument is a key invented by Highten, consisting of a couple of springs, one marked + and the other -, connected one with the earth and the other with the line. When these springs are at rest, or pressing upwards, the line and the earth are in connection with one another, and with the positive pole of the battery, the negative pole being insulated. When the earth-spring marked -I-, is pressed down by the finger, the earth connection is thrown on the negative pole, and the positive pole is left on the tele graph line, which thus receives a positive current. When the line spring marked - is pressed down, the positive pole of the battery is left in connection with the earth, and the line is thrown into connec tion with the negative pole of the battery, and will thus receive a negative current. Now it is perfectly easy to make the two bells take the place of the gold strip, and calling the left-hand bell I, and the right-hand bell 3, Highton'a nomenclature becomes applicable. The receiving-clerk is seated between the two hells, and his ear being alone engaged in receiving the signals, he can write down the letters which they represent as easily as when one clerk is employed to watch the needle, and dictate the message to another who writes it down. Whether this system may not induce an increased amount of nervous ness in the clerks employed, we are not able to say, but it is stated that the use of the ordinary needle telegraph is apt to produce nervous irritability in the clerks who are long employed upon it.
A considerable advance has recently been made in telegraphs in con sequence of Professor Wheatstone:1'a copious list of improvements in the whole of the telegraphic system, embodied in two patents dated 2nd of June, 1858, and numbered respectively 1239, 1241. We give these numbers in order that persons interested in the subject may the more readily procure the printed copies of the specifications, which are accompanied the one by six and the other by ten sheets of illustrative engravings. The basis of this invention is the Letter Telegraph of 1839, now called the Universal Telegraph; and it is so simple in its action that no training is required to use it ; for the message may either be spelt out on a dial by bringing common letters opposite a fixed point, the neoessary electrical currents being developed by an ordinary voltaic battery, or, still better, by induction from a permanent magnet. This telegraph is being rapidly adopted In London, where it forme the London District Telegraph ; and also throughout the country by men chanta and manufacturers, as a means of communication at their offices and establishments at a distance ; also from one portion of a large warehouse to another, between the several heeds of departments and the manager's room, through mills and public works', or wherever the constant transmission and receipt of intelligence is of importance. This system has been in use at the London Docks during the last few years, and also servos to communicate betweeu the Houses of Parlia ment and her Majesty's printers iu Shoe Lane. All we can pretend to do in this place is to give a brief outline of the more important fea tures of this invention. It is described am Wheatstone's Automatic Printing Telegraph, and is capable of printing 500 letters per minute.
The order and succession of the electric currents are determined by perforated bands of paper, somewhat after the manner of the cards in a Jacquard loom. The different letters are *presented by groups of points, fie. 16, and these, when arranged for a message, arc separated by smaller points, fig. 17, so as to prevent any mistake from the coalescence of adjacent letters, and the characters are printed without adding to the weight or causing any resistance in the moving parts of the electro-maguets. The invention consists of a new combination of mechanism, for the purpose of transmitting messages previously pre pared through a telegraphic circuit, and causing them to be printed at a distant station. Long strips of paper are perforated by a machine, provided with apertures so grouped as to represent the letters of the alphabet and other signs (h. 17) : a strip thus prepared is placed iu an instrument associated with a source of electric power, which on being set in motion moves it along, and causes it to act on two pins, in such a manlier that when one of them is elevated the current is transmitted to the telegraphic circuit in one direction, and when the other is elevated it is transmitted in the reverse direction : the elevations and depressions of these pins are governed by the apertures and intervening intervals. These currents following each other indifferently in these two opposite directions act upon a writing instrument at a distant station in such a manner am to produce corresponding marks on a slip of paper (fig. 18) moved by appropriate mechanism.
Each part of this telegraphic system is stated by the inventor to have its independent originality and to be capable of association with other forms of apparatus already known. The first of these inventions is an instrument called a Perforator for piercing the slips of paper in the order required to form the message. The slip passes through a guiding groove, at the bottom of which is MI opening large enough to admit of the to-and-fro motion of the upper end of the frame containing three punches on a level. Each of these punches, however, may be separately elevated by the pressure of a finger-key, and at the moment of its elevation two different movements are successively produced. 1st, a clip is raised, which holds the paper firmly in its position ; 2nd, the frame containing the three punches advances, by which the punch which is raised carries the ribbon of paper forward the proper distance; during the reaction of the key consequent on the removal of the pressure, the clip first fastens the paper and then the frame falls back to its normal position. The two external keys and punches are employed to make the holes, which grouped together represent letters and other characters, and the middle punch makes the holes which mark the intervals between the letters. A simple addition to the perforator enables a printed message which has been received to be retransmitted to a more distant station, without any translation or knowledge of the meaning of the meetage. The printed band passes between two rollers, one of which is moveable by a finger-screw, so am to cause the characters to pass successively before the eyes of the operator. The keys of the perforator are acted upon with the right-hand and the finger-screw with the left ; as the craters surely appear the keys are pressed down in the order of the points of which the letters consist, an operation which scarcely requires any skill to perform, and which needs no change in tho alphabet usually employed, the points at one side representing the short dashes, and those at the other side the long daehes, tho order usually observed remaining the same.