A TELEGRAPHIC EXPERIMENT.

Otago Witness, Issue 1248, 30 October 1875, Page 19

A TELEGRAPHIC EXPERIMENT.

We are accustomed to talk familiarly of the wonders of telegraphy, but it is not till we are brought face to face with what can be done by the aid of the telegraph that we realise them. An experiment which is probably unique in the history of tekgraphy, was conducted on Saturday evening by Mr John A. Lund (of Messrs Barraud and Lunds, Cornhill), at the offices of the Indo-European Telegraph Company. It was desired by Captain Sarturius, brother' to the captain of the Ashantee celebrity, who is at Teheran, Persia, to check with absolute correctness, the variation between one of the clironometers of this firm which he had there and the Greenwich time here. To do this it was necessaiy to have the line clear from London to Teheran, a distance of 3700 miles. Major Smith, the telegraph superintendent, was with Captain Satnrius at the Teheran instrument, and Mr Black was in charge of the London instrument ; while Mr Lund was in attendance with a ship's chronometer, set to exact Greenwich time. The time here was eight o'clock, equal to about half-past ll p.m. in Persia. The first message transmitted broke at Berlin, where the Vires had not been coupled ; but shortly afterwards the message was sent through from Teheran, and was uncoiling itself on the long tape, like a piece of paper, at the Moorgate street instrument : — " Give the signal current at nineteen past eight, and keep it on till twenty." This was affected by holding down the small handle which connects the zinc and copper wires, thereby causing a current for the space of the minute indicated— Mr Lund calling out "fifty-eight," "fifty-nine,"" sixty," as the seconds went by which completed the minute. At the word " sixty, " the handle was loosed, and Captain Sartoriu3 would the same instant know that it was 8.20 p.m. Greenwich time. To check the minute differences of individual observations, the experiment was repeated two or three times, the lesult being that Captain Sartorius's was shown to be about two seconds behind Greenwich time. While the current was flowing, its duration was marked by a long black line on the paper at Teheran, and when it stopped there would be a sharp " click." as the pressure on the London handle was removed. Perhaps the most marvellous fact about the whole thing is that (as is well known to telegraphists) the " earth current " or stream of electricity which completes the circuit from battery to battery, finds its way through the earth from 'Teheran to London without any wire or other connection whatever till it finds the battery from which it started, and this, too, instantaneously.