giving out, they rise; and again at night, when less is being pumped
into them than is going out for consumption in the streets and houses,
they fall. The gasholder is placed in a tank of water, so that there
is no waste of gas as the huge iron holder fills or empties.

Now it was in one of these gasholders that a few years ago two men did
a deed that will live. Here is the brief story.

The holder was being repaired, the gas had been removed, and air had
been pumped into it instead of gas so that men could work inside, and
the holder had risen about fifty feet. Two men were working inside the
holder, one a foreman, and the other a labourer named Case, the latter
in a diver's helmet. They were standing on a plank floating on the
water. Fresh air was being pumped down to Case, who, so long as he
kept on the helmet, was perfectly safe.

All at once the foreman found he was beginning to feel faint, so he
told the labourer they would go up to the top for fresh air. But he
had not the strength to carry out his purpose. The raft was pulled to
the ladder by which they were to get out; but he was unable to ascend,
and fell down in a fainting condition.

Then the labourer, regardless of the danger he was running, unscrewed
his helmet, into which fresh air was being pumped, and, placing it
quite near his fallen comrade, enabled him to get some of the air. The
foreman tried in vain to get Case to put on the helmet; and his own
strength was too slight to force him to do so. Indeed, he was in such
a state of weakness that he fell on the raft, and knew no more till he
once again found himself in a place of safety.