spring. Then presently this
illusion passes, and you see everything flat. There are no hills any
more, nor villages; no towers nor steep descents, only a level surface,
marked charmingly in color, sometimes in wonderful mosaics, and
strangely in light and shade. At the height of two miles nothing is
familiar; you might as well be looking at the moon, for all you can
recognize. Roads become yellowish lines; rivers brownish lines (and the
water vanishes); a mountain-range becomes a shaded strip, with less
shade on one edge (where the sun is) than on the other; a forest becomes
a patch of color; a town another patch. There is scarcely any difference
between water and land, and you see to the bottom of a lake, so that the
configuration of its bed in valley and hill are apparent through the
color and the shading. This singular disappearance of water bodies, for
it amounts to almost that, has an evident importance.

"I'll tell you what we did on Lake Ontario," said the professor, "as a
result of observations I made there from a balloon. In sailing over the
lake on one occasion I remarked a number of small shaded spots which
puzzled me. I could not imagine what they were. Finally, with the help
of powerful field-glasses, I made them out to be wrecks sunk at various
depths, and I realized that Lake Ontario, and indeed all the great
lakes, abound in vessels which have gone down during centuries and never
been recovered. No one can estimate the treasure which lies there
waiting for some one to reclaim it. And I saw that it is a perfectly
simple matter to locate these wrecks from a balloon, and to prove this I
organized a modest wrecking expedition, and indicated to the diver where
he was to go down. Down he went at that point, and found the wreck I had
seen, and we pumped good coal out of her by hundreds of tons. What I
did then on a small scale might be done on a large scale by any one
willing to undertake it."

Of course I asked the professor why it is that an aeronaut can see down
into a lake better than, say, an observer in a boat, and he explained
that there is a great gain in intensity of terrestrial illumination when
the viewpoint is at a height, because the sun's rays converge toward the
earth, the sun being so many times larger, and therefore (this is his
theory) a man lifted above the earth gets many more solar rays reflected
to him from a given area than he would get if nearer to that area. In a
word, it is a matter o