_Whistling Buoys._--The whistling buoy now in use was patented by Mr. J.M.
Courtenay, of New York. It consists of an iron pear-shaped bulb, 12 feet
across at its widest part, and floating 12 feet out of water. Inside the
bulb is a tube 33 inches across, extending from the top through the bottom
to a depth of 32 feet, into water free from wave motion. The tube is open
at its lower end, but projects, air-tight, through the top of the bulb,
and is closed with a plate having in it three holes, two for letting the
air into the tube, and one between the others for letting the air out to
work the 10-inch locomotive whistle with which it is surmounted. These
holes are connected with three pipes which lead down to near the water
level, where they pass through a diaphragm which divides the outer
cylinder into two parts. The great bulb which buoys up the whole mass
rises and falls with the motion of the waves, carrying the tube up and
down with it, thus establishing a piston-and-cylinder movement, the water
in the tube acting as an immovable piston, while the tube itself acts as a
moving cylinder. Thus the air admitted through valves, as the buoy rises
on the wave, into that part of the bulb which is above water, is
compressed, and as the buoy falls with the wave, it is further compressed
and forced through a 2½ inch pipe which at its apex connects with the
whistle. The dimensions of the whistling buoy have recently been much
diminished without detracting materially from the volume of sound it
produces. It is now made of four sizes. The smallest in our waters has a
bulb 6 feet in diameter and a tube 10 feet in length, and weighs but 2,000
pounds. The largest and oldest whistling buoy has a 12-foot bulb, a tube
32 feet long, and weighs 12,000 pounds.

There are now 34 of these whistling buoys on the coast of the United
States, which have cost, with their appurtenances, about $1,200 each. It
is a curious fact that, in proportion as they are useful to the mariner,
they are obnoxious to the house dweller within earshot of them, and that