MAN'S SUBMARINE WORK. 381 



At first this armor was made of cloth impervi- 

 ous to wafer, 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 hislip3 a tube connecting 

 with the air chamber, and breathes as naturally as 

 if on land. 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 

 which is 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 



