THE SIGNAL OR SEMAPHORIC TELEGRAPH.
This is a most ingenious invention, for the purpose of carrying on a communication with distant persons. The line of Telegraphs, or stations (eleven in number), was established by the Trustees of the Liverpool Docks; they extend along the coast as far as Liverpool, and are fixed on commanding heights, at an average distance of a little less than eight miles apart. A constant look-out is kept during the day at each of these stations. The rapidity with which a communication is made from Holyhead mountain to Liverpool, a distance of about 80 miles, is truly astonishing. A question is sometimes asked at Liverpool, and an answer received from Holyhead in less than a minute,—on some occasions in 30 seconds. The ordinary intelligence of what ships are in sight, &c., is generally conveyed in 5 minutes. The Telegraph consists of two vertical columns. Each of these columns is provided with two pairs of arms, moveable on pivots, at a sufficient distance from each other to prevent any confusion in the working. There are thus eight arms, which, when out of operation or indicating a cipher, or the ciphers required in expressing hundreds and thousands, are invisible within the mast. Each arm is capable of three points of elevation, and is worked from below by means of chains hitched on to levers of a peculiar construction. Any number, from 1 to 9, is indicated by one or both of the arms being pointed obliquely or horizontally. This arrangement of motion is applicable to each of the four pairs of arms; but otherwise, each has a different arithmetical power, indicating units, tens, hundreds, thousands; so that the four powers in combination are capable of exhibiting every number from 1 to 9,999; but in order to extend the number still further, each mast is provided with an indicator, or board, working vertically on its summit; these indicators, when not in operation, being invisible. By this means four series of numbers, from 1 to 9,999, may be obtained, the telegraphic powers being extended to 39,996 signals. Contiguous to this telegraph is one of older date, connected with the Holyhead Harbour.