e batteries
to further a plot. Outside of scientific work the batteries would not
be likely to be used anywhere except on board a submarine. Storage
batteries of different size and pattern are used for industrial
purposes, but those described in this bill are used on board
submarines."

"Your reasoning is plausible, Darrin, and probably correct, too,"
nodded Admiral Timworth.

"Besides which, sir," Dave pressed home, "if we admit that the
plotters have conspired to sink a British battleship at Malta, the
easiest way in war-time, when unidentified strangers cannot get aboard
a warship, would be to effect the sinking by means of a submarine's
torpedo. And, if this be the plan of the plotters, then the crime is
likely to be attempted only when there are British and American war
craft, and none others, in the Grand Harbor of Malta."

"Yet surely the plotters must know that, between good friends like
Britain and America, it would take more than the mere sinking of a
British ship to make the English suspect us, as a nation, of being
involved in such a dastardly plot."

"Our country couldn't be suspected, as a government or a nation, of
being guilty of such a wicked deed," Dave answered. "But Englishman
and Frenchmen might very easily believe that the torpedoing was the
work of a group of officers and men in our Navy who hated England
enough to strike her below the belt. With the British ship sunk, sir,
and with none to suspect but the Americans, there is no telling to
what heights British passion might rise. The British are feeling the
tension of the great war severely, sir."

"There is one flaw in your reasoning, Mr. Darrin," Admiral Timworth
replied. "We will admit that the torpedoing happens at a time when
only American and British war craft are visible in Grand Harbor. Why
would it not be wholly reasonable for the British to suppose that the
torpedoing was the work of a German submarine that had sneaked into
the harbor of Malta under the surface of the water?"

"That occurred to me, sir," Dave admitted, "and at first I couldn't
find the answer, but at last I did."

"I shall be glad to hear that answer."

"The submarine, let us suppose, sir, discharges one torpedo with such
accuracy as to sink the British battleship. Why could not another
torpedo be fired immediately, which would not strike, but would rise
to the surface and be afterwards identified when found as an American
torpedo? For a torpedo that does not