t. I find by experiment that when the
two rays are switched on simultaneously the air does not become
de-oxygenised, but when you put the violet ray first it does, and it
remains so until the orange ray is applied. The effect that Hilderman
imagined, and succeeded in producing, was a ray of light which should
so alter the relative density of the air as to act as a telescope.
He's done it, and it's one of the finest achievements of science.
However, I have a piece of wonderful news for you."

"What is it?" we both demanded at once.

"The Secret of the Green Ray is ours, and ours alone. Hilderman has
admitted that the reason why they did not clear it out at the first
sign of suspicion was that, in their final calculations, they were
unsure of their figures. That means, put popularly, that though he
knew what he was trying to do, and how he meant to do it, the actual
result was something of a fluke. It very often is with inventors. They
had no drawings that they could rely on to make another searchlight
by, so they were bound to take the whole thing back with them. They
could send no figures, because the relative distances and other
quantities baffled them. They could not take the searchlight back in
pieces, because if any piece had been broken they might not have been
able to reconstruct the proportions with critical accuracy, as we say.
So what was to have been Germany's hideous weapon of war is now ours.
We have a searchlight which acts as a telescope, which will pierce the
deepest fog, and which will dispel the most ungodly poisonous gases
ever invented. You can see for yourself that no gas could make headway
against the atmosphere you encountered the other day. Armies and
navies will be absolutely powerless to advance against it. The green
ray is the fourth arm of military power. So you see what you've done
for your country, you lucky dog!"

"_I!_" I cried. "I like that! I've had less to do with it than
anyone. What about you, eh?--coming running up with a gunboat at the
critical moment. How did you manage that?"

"Well," he replied, "as soon as I was in the train on my way back I
solved the problem of the fateful hour--with your help, of course. You
pointed out that only then was the whole of the gorge flooded with
sunshine. Now, it struck me that, if it were not electricity, it would
be heat or some other form of light. Then it flashed into my mind that
if it were done from a searchlight possessed of some devili