MONTREAL, June 12, 1891.—The observatory of McGill University here has been conducting some very interesting experiments, preparatory to getting into shape to be connected with the Astronomer Royal at Greenwich, so as to determine the exact longitude of Montreal and other points on the Atlantic seaboard. In order to work out their calculations it was necessary for them to determine the exact time it took for a telegraphic signal to cross the Atlantic. Last Sunday McGill Observatory was connected over the Canadian Pacific Railway's telegraph, with the Commercial Cable Station at Canso, N. S., where Mr. S. S. Dickenson, the superintendent of that company, had arranged an automatic contrivance so that the land line and cables should work into each other.

When this was done a duplex circuit was arranged on both land and sea between the observatory at Montreal and the Commercial Cable Company's station at Waterville, Ireland. A chronograph was attached to this end of the circuit, and the telegraph signal that was sent from McGill Observatory to Canso, across the ocean and back again, came back to the point from which it started, and was recorded on the chronograph. One hundred and twenty signals were sent through the round circuit of 8,000 miles of wire and cable, and the average time of transmission, from the time that the signal left McGill Observatory until it returned, proved to be one second and five-hundredths. The whole number ranged between the narrow limits of one second and one and one-tenth seconds—HERALD, N. Y., June 13, 1891.

LONDON AND BACK IN SIX MINUTES.

One of the leading firms of arbitrage brokers in this city sent a message yesterday morning, from the Stock Exchange office of the Mackay -Bennett Co., to London. The business referred to in the message was transacted and the answer received in New York in the space of six minutes—the quickest time on record—Herald, New York, Jan. 29, 1886.

LONDON AND BACK IN THIRTEEN MINUTES.

One of our local magnates sent a cablegram to London, via the Commercial Cable, this morning, at 10.27, and at 10.40 he had a reply—just thirteen minutes. In this time the message was sent from Montreal to Canso, thence to Ireland, where it was reported to London. A transaction was effected on the London Stock Exchange, the reply written and came traveling back again, reaching the sender in thirteen minutes.

The gentleman could scarcely credit it, but 011 examination of his sent message and his reply thereto, found the facts to be as above.—Daily Witness, Montreal, Oct. 30, 1890.

In December, 1884, a communication was sent from New York to London, and an answer received in forty-five seconds. This feat was accomplished over the Commercial Cables, and is the fastest time on record.

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