The purchase by the British Admiralty of the motor-driven torpedo boat, built and successfully tested last winter by Messrs. Yarrow, must be regarded as an official indorsement of a new type of fighting craft. The vessel was built entirely on the responsibility of Messrs. Yarrow, and under the conviction that there would be a wide field of usefulness in store for it, as forming part of the naval defenses of estuaries and harbors. The original idea of the torpedo-boat fiotil- las was that they should consist of a large number of small and comparatively cheap units, each possessing high speed, and exposing only a small area to gun fire. In recent years, however, in the endeavor to secure higher speeds, there has been a steady departure from at least two of these essential principles. The boats have grown larger and more costly, until, from the original size of 75 feet, they have grown to an overall length of 150, with a proportionate increase in the cost. The builders of this craft believe that it will be possible, by making use of internal-combustion engines, to return to first principles in these two respects, without sacrificing too much of the present high speed. The small size of these boats would enable them to form part of the boat equipment of battleships and cruisers. The earlier attempts to carry torpedo boats on warships failed, because the restrictions on size rendered it” impossible to install steam engines of sufficient power