MAN’S SUBMARINE WORK. 3881 
At first. this armor was made of cloth impervi- 
ous to water, but it soon wore out or became punc- 
tured by sharp rocks or nails about a wreck so as 
to admit water, and become useless. The discov- 
ery of India-rubber and the great improvements in 
working iron and steel have made it possible to con- 
struct a diving armor which is nearly perfect. It 
can be put on in a few minutes—the flexible joints 
allowing great freedom to the diver. The mask for 
the face and head can be opened and closed in a mo- 
ment, and the diver carries down with him a supply 
of air in a light steel chest or knapsack on his 
shoulders. This supply is kept fresh and full, by 
means of a pipe communicating with a pump above. 
The diver takes between his lips a tube connecting 
with the air chamber, and breathes as naturally as 
ifonland. The. air which escapes from his lungs 
at each expiration rises to the surface in bubbles 
just as regular as his breathing, giving notice to 
those above that the diver is alive. Should the air 
bubbles cease to rise, that would be evidence that 
he had stopped breathing, and he would be instant- 
ly drawn up to the surface by means of a cord 
whichis attached to him for that purpose. Should 
the breathing as shown by the bubbles be irregular, 
then it would be evidence that the diver was in 
some trouble. 
The steel air-chamber is admirably contrived for 
the purpose. No matter how fast the pump above 
is operated, it does not affect the diver. He can draw 
from his air-reservoir at his convenience, and when 
he stops drawing, no air can escape, for a valve is 
