tions against
night raids by the airmen. Mining the air consists of locating small
balloons over an area, each balloon being attached to the other with
wires. The small balloons have attached to them explosive bombs which
would destroy the larger aircraft if it was to run into this nest of air
vessels in the dark.

Reverting to the use of aircraft in naval warfare it may be said that to
the aeroplane the relatively fast fleet is virtually stationary. About
the only case parallel to the aeroplane looking over the hill and down
on concealed enemy positions would be in rising above the smoke screen
thrown out by destroyers.

THE SMOKE SCREEN.

The smoke screen, by the way, which has been used by the British with
marked success in many instances, is an American invention. The low,
swift craft are equipped with special oil burners which throw off dense
volumes of heavy smoke, which float low over the surface of the water,
concealing the maneuvers of the larger boats and protecting them from
the skill of enemy gunners. Its effectiveness, of course, is influenced
by the direction and strength of the wind. Used generously by small
craft convoying a ship through a submarine area, it should be of great
value.

A battleship can see about as far as it can shoot, anyhow. Except for
smoke screen, or the famous "low visibility," which means foggy weather
or darkness, no enemy within range can be concealed.

What the fleet commander wants to know is how those enemy vessels beyond
the horizon, which may be within range of his guns tomorrow, the day
after, or next week, may be distributed, and how many of them there are.
This is where the speed of the airplane comes in.

A machine which can travel 100 miles an hour covers a thousand miles in
10 hours. Locating an approaching enemy fleet this distance away, it
brings back the news of the approach in 10 hours. It takes the fleet,
traveling at 15 miles an hour, two days and 18 hours to cover this
distance. The aeroplane can beat it by two days and eight hours.

But the aeroplane flying high enough to give it the widest practical
range of vision is able to see only over a path 75 miles wide under the
most favorable weather conditions. Haze will cut this down considerably.
This means that for anything like complete scouting work a fleet must be
equipped with a large number of them.

PROPORTION OF FIGHTING PLANES.

Then, too, there must be a generous proportion of fighting plane