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on the side of the attack. The range and power of the electric light is so diminished by fog or mist as to make it practically useless at such a time. This is due to its deficiency of red rays, which are not absorbed by aqueous vapour to the same extent as the other components of white light. The smoke of guns is even more embarrassing, while the difficulty of hitting a small object moving at a speed of 20 knots had not hitherto been appreciated.
Two causes only could be relied upon to stop torpedo boats in an attack of this nature. One is a fixed obstacle, as a boom which cannot be jumped, and the other is to have a sufficient number of small craft with speed and power to grapple the boats before their object is reached. The former can only be used in certain places, and there would be difficulty in applying it to the entrance of Portsmouth Harbour, where the current is so swift. But there is nothing to prevent an effective patrol by guard boats. Unfortunately, hitherto little had been done in this direction. The military had seen the necessity as a protection to their mines, but had not the means for carrying it out, while the Navy, not having control of the local defence, did not consider it their province. Alive now to the risk of having no mobile defence, a few steam launches had been hastily equipped, and with one or two of the new catchers had been sent to patrol outside Spithead. Warned by the signals of the
