nt that the other had failed to
whistle: yet witnesses testified that both had whistled, and each one
swore that he had.

The truth was, according to the gentlemen who explain acoustic puzzles,
that these two steamers happened to be placed there down the bay like
two people in a whispering gallery, who cannot hear each other where
they are, but would hear plainly if they moved further apart or drew
closer together, so as to be in the foci of sound. Thus it was that
distant vessels heard both sets of whistles, although there was a nearer
region where these were inaudible.

Investigation has shown that these sound zones frequently establish
themselves at sea (they vary in extent with wind and tide), so that the
sound of horn or bell may be heard for a mile or two, and then become
inaudible for, say, two miles, and then become audible again, almost as
plainly as at first, for several miles more. The theory is that the
sound-waves somehow go skipping over the sea, like a flat pebble over a
mill-pond, in long jumps, and that a vessel under the highest part of
one of these jumps is out of the sound influence, but will come into it
again by going ahead a certain distance or going back a certain
distance. Whether this explanation be the true one or not, the facts are
abundantly vouched for, and are believed to explain various collisions
and wrecks that have long been looked upon as mysteries.

"There are lots of queer things about our business," reflected an old
pilot. "Now, you take steamers, they're just as different as people;
each one has her own ways, and most likely her own partic'lar kind of
crankiness. They talk about twin steamers, but there's no such thing.
You can have 'em both made in the same yard, with every measurement
alike, and they'll be as different, sir, as--as two violins. Why, I
never saw a craft that'd sail the same on both tacks; they're always
harder on one than the other. And as for compasses--well, I don't
suppose there's ever two that came into this port with needles pointing
just the same way. They all lean a shade one way or the other, same as
watches."

"Lean a shade!" put in another man. "I've known 'em to lean a whole lot.
I've known a steamer's compass to point plumb northeast instead of
north. And that time we nearly went on the rocks by it. We were coming
along past Fire Island, and the night was pretty thick. I felt something
was queer and wouldn't go below, although the captain wanted m