m confirmed invalids.

INTRODUCTION OF GAS MASK.

Naturally human ingenuity was called into play to protect men against
the poisons and the gas mask came into being. These were of many types.
The early creations consisted primarily of a nose and mouth covering
with a receptacle for inclosing a sponge or gauze soaked with a chemical
which possessed the power to neutralize the gas fumes. Such devices have
been used by fire fighters in large cities the world over where the men
battling to save buildings have been compelled to enter smoke-filled
rooms and cellars. Other types which have proven more effective are
designed after the fashion of the diving apparatus, and having a small
tank of compressed oxygen with feeding tubes running to the mask. The
oxygen combines with the contaminated air breathed through absorbent
cotton or sponge and provides the wearer with the proportion of oxygen
necessary to existence. And even the horses have been provided with such
masks.

But to go back to bombs. All through France and Belgium, and wherever
the Prussian soldiers found their way, there was evidence of the use of
hand grenades which were thrown against the sides of or into buildings
to set them in flames. Some of these devices, made of sheet metal, were
in their action similar to the "Fourth of July torpedoes" familiar to
every American school boy. When thrown they exploded throwing oil and
chemicals over walls and floors. Some of them seem to have been loaded
with bullets and were in effect hand shrapnel.

Then there developed from the primary use of these nefarious weapons the
recognized hand grenade, which is actually hand-shrapnel, plied by men
at close quarters. Thousands of these have been thrown by the armies in
their charges on the trenches. And then, to offset the use of these
devices in the offensive, there came into being also the smoke bombs.
These when exploding throw up great clouds of black smoke which hang
over everything.

EFFECTIVE IN A HUNDRED WAYS.

The use of such bombs has proved effective in a hundred ways. They have
been used to create a perfect shield of smoke to conceal the movements
of troops, or prevent the enemy from finding the range with their long
distance guns. Similarly bombs which contained burning chemicals have
been used to hold in check the approaching enemy forces.

Half way between the great gun and the hand grenade stand among war
weapons the trench mortars. The first of these w