showing
a prolonged flash of ten seconds duration once in a minute. The light
is about three hundred and sixty feet above the sea, and with a clear
atmosphere is visible, from a position ten feet high, twenty-five and a
half miles distant; from an elevation of sixty feet, it can be seen nearly
thirty-one miles away; and it is plainly visible from Sulphur Peak on the
main-land, thirty-four hundred and seventy-one feet high, and sixty-four
and a half miles distant. The light-house is in latitude 37 deg. 41' 8" north,
and longitude 122 deg. 59' 05" west.

On our foggy Western coast it has been necessary to place the light-houses
low, because if they stood too high their light would be hidden in
fog-banks and low clouds. The tower on the South Farallon is, therefore,
low; and this, no doubt, is an advantage also to the light-keepers, who
are less exposed to the buffetings of the storm than if their labor and
care lay at a higher elevation.

As the Farallones lie in the track of vessels coming from the westward to
San Francisco, the light is one of the most important, as it is also one
of the most powerful on our Western coast; and it is supplemented by a
fog-whistle, which is one of the most curious contrivances of this kind
in the world. It is a huge trumpet, six inches in diameter at its smaller
end, and blown by the rush of air through a cave or passage connecting
with the ocean.

One of the numerous caves worn into the rocks by the surf had a hole at
the top, through which the incoming breakers violently expelled the air
they carried before them. Such spout-holes are not uncommon on rugged,
rocky coasts. There are several on the Mendocino coast, and a number on
the shores of the Sandwich Islands. This one, however, has been utilized
by the ingenuity of man. The mouth-piece of the trumpet or fog-whistle is
fixed against the aperture in the rock, and the breaker, dashing in with
venomous spite, or the huge bulging wave which would dash a ship to pieces
and drown her crew in a single effort, now blows the fog-whistle and warns
the mariner off. The sound thus produced has been heard at a distance of
seven or eight miles. It has a peculiar effect, because it has no regular
period; depending upon the irregular coming in of the waves, and upon
their similarly irregular force, it is blown somewhat as an idle boy would
blow his penny trumpet. It ceases entirely for an hour and a half at low
water, when the mouth of the cave o