d feet of tubing to convey air to his helmet, and as this was more
than one man could drag after him, two other divers were called upon to
assist. One descended to the bottom of the shaft, while another walked
up the 'heading' for five hundred feet, passing Lambert's air-tube along
as the latter continued the terrible journey alone. Stumbling in the
darkness over the scattered tools which the escaping workmen had thrown
down, he arrived at last within a hundred feet of the door--only to find
that he had not the strength to drag the air-hose any farther! Floating
upwards in the water, it rubbed too hard against the ceiling of the
tunnel to be pulled downwards and onwards. Lambert sat down, and, by a
supreme effort, pulled it a few feet more. But the task was beyond his
strength, and, greatly disappointed, he returned to the bottom of the
shaft.

A few days later he tried again. This time no air-hose was used.
Strapped on his back he carried a vessel filled with condensed oxygen
gas, which he could admit to the helmet in small quantities at will.
Groping his way once more along the narrow, water-choked passage, he at
last reached the door. Passing through to the other side he felt for the
open end of one of the pipes, and turned the screws of its valve. Then,
stepping back, he shut the door behind him. All that now remained to be
done was to seal the second pipe. This had what is called a sluice
valve, and Lambert had been instructed to turn the screw which closed it
round and round, until he found he could turn it no farther; when that
was done, he would know that it was shut. It took some time, but it was
accomplished at last, and the triumphant diver returned to the upper
air. He had been absent one hour and eighteen minutes.

Lambert had done well, and all were ready to acknowledge his great
courage; but the water, strange to say, remained abundant, and it was
only after still further increasing the size of the pumps that it was at
last got rid of. Then the secret came out: no one had told Lambert that
the sluice valve had a left-handed screw, and that, therefore, to close
it he would have to turn it in the opposite direction to the usual one.
So all his heroic labour was expended on opening the valve to its
fullest extent, and thwarting the purpose for which he had undertaken
such a perilous duty.

This spring proved to be the greatest enemy the engineers had. But on
one occasion the sea itself made an attack upon