It is practically impossible to give any idea of the extent to which wireless transmission is in operation, not only on passenger vessels, but in the case of cargo boats, cable-laying vessels, lightships, private yachts and other classes of vessel apart from the navies of the world. But the following list of the communications effected day by day in the case of a typical Atlantic vessel will indicate the importance of wireless telegraphy in one of its most conspicuous phases—a trans-Atlantic voyage on a large liner:—

It may be of interest to observe that of all the communications effected as above noted, in only one case, namely, that the Scheveningen (Holland) was the corresponding station not fitted with Marconi apparatus.

The use of wireless telegraphy on cable-laying vessels, yachts and other special classes of ship is increasing. At present the following cable-laying boats and private yachts have been equipped by the Marconi Company:—

s.y. “Iolanda.” s.y. “Cassandra.” s.y. “Atalanta.”
s.y. “Lysistrata.” s.y. “Niagara.” s.y. “Florence.”

c.s. “Mackay Bennett.” c.s. “Colonia.” c.s. “Cambria.”
c.s. “Buccaneer.”

The conditions under which cable-laying vessels have to work make the value of wireless telegraphy very conspicuous in their case. Repairs have to be carried out at long distances from shore, and as a rule the vessels have to return to port before instructions regarding subsequent work reach them, with the result that expensive delays are frequently incurred. An example of the service which wireless telegraphy may render is supplied by the following extract (modified in details of wording) from the log of a cable-laying ship:—

On one occasion we were repairing a cable some 180 miles from the west coast of England, and required further information about electrical tests from the shore. A message was sent and received by another steamer equipped with a Marconi wireless installation and relayed by her on to England, the result being that in less than an hour we had a reply from London giving the desired information, and enabling the vessel to proceed with her cable-laying operations without delay.
Considering that the inquiry was relayed, and necessitated a careful answer from headquarters, also relayed, the time occupied was remarkably short. On another occasion, when the vessel was on her way home from the completion of a repair off Ireland, a wireless message was received ordering her to the coast of France for another repair, thus saving a useless voyage back to London.

The standard equipment for marine work is either the 11/2 kw. set just described or a 5 kw. set, where a disc machine takes the place of a spark discharger. Both sets are capable of exceeding their guaranteed limits. For instance, in the case of certain destroyers, the guaranteed range of transmission was 60 miles, but nearly all of them exceeded 80 miles on their tests. In the case of a larger vessel, the guaranteed range was 100 miles and the realised range was 185 miles. Another warship fitted with a 5 kw. installation exceeded her guaranteed range of 250 miles by more than 100 miles.

As already indicated, the number of wireless installations on shore and on ships is increasing so rapidly that up-to-date official statistics covering the whole of the world are impossible to obtain. The following figures, taken from the Bulletins of the International Telegraph Bureau, will give some notion of the extent of the business, but they must not be taken as complete, since certain countries have not ratified the Convention or made complete returns.

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