Evening star., 1925-09-13
Copyright by Underwood & Underwood.

tween the crotch of the dress and the
helmet can be regulated to prevent
| the latter from rising over the divers
| head when the dress is filled with air.
| Canvas overallS also are worn to
protect the suit and. If necessary,
heavy gloves are used to protect the
| hands from the cold.
| The helmet, to which is attached the
| air hose, life line and telephone, the
| last two mentioned generally being
| combined into one. is the most impor-
| tant item of the outfit. 1t contains the
delicate mechanism which enables it's
wearer to receive an even flow of air
from the pumps or torpedo air TASKS
above. BY control valve placed in
the air hose the diver regulates the
flow of high-pressure air into the head
dress. Another valve, which opens
automatically when the pressure with
in the suit is greater than that of the
water without, allows the used air to
escape into the water. Glass portfolios,
which give the helmet a grotesque ap-
pearance, are protected by metal graf
ing and give the man within a for
ward, lateral and upward view.
Telephone cable and life lire are
combined into one line, which serves
as a means of supporting the diver
when off the bottom. In case of acci-
dent to the telephone, reserve signals
] IlldN De transmitted Df using Ine cable
| as a signal line.
In communicating with the diver by
telephone the effects Of pressure are
| noted on the divers voice, which suf-
fers loss of timbre the quality as dis
| tinguished from intensity and Pitch.
However, there is little difficulty in
understanding him at depths as great
as 300 feet, if moderate voice is en-
! ployed.
Few Y>hUSicoll,r ah %
stand the strain under which the diver
| must work constantly. Fat men are
| barred from this profession, and in
! selecting men for the Navy Diving
| School thin, wiry men of a phlegmatic
temperament are chosen. Here circula.
ton is faster, and after working at
great depths the diver desaturates
more quickly and is less liable to
| caisSon disease.
Uncle Sans divers are rated in two
classes. Only those of the first class
are permitted to descend more than 80
feet.
Artificial atmosphere experiments
being conducted at present by the
United States Bureau of Mines, with
a view to reducing casualties from
compressed air illness, indicate that
the field of undersea work is likely to
undergo complete revolution i'll the
very near future. Using a mixture of
henum and oxygen, instead of ordi-
nary air, which is composed mainly
| of oxygen and nitrogen, Government
experts have subjected guinea pigs
| and white rats to enormous pressl,res
| without the subjects experiencing the
| distress which often follows the Use
, of air.
Although the tests with men have
been too few for satisfactory conclu-
sions to be drawn as yet, the results
are very gratifying, and indicate that
when the method is perfected divers
may be lowered to two or three times
the depths now attained without sI1f
fering any i'll effects.
4 X
e IA1SSON disease, the Divers great
| est terror, can be explained very
simply. During compression and at
/ working pressure the fluids and tis-
sues OF the body absorb large volume
OF air in accordance with the physical
law governing the solubility of gases
in liquids. While the diver is under
| going. pressure this absorption of an
abnormal volume of gas seems to have
no effect whatever. In fact, the speed
with which man may be compressed
| or lowered into the water is governed
almost entirely by the effect on his
ears, improper functioning of the
| eustachian tubes, which serve to
equalize the pressure on the two sides
of the eardrum, being followed by
serious consequences.
Aside from this difficulty, which is
not a serious one with experienced
underwater workers, it is to the
divers advantage to go under pressure
rapidly, and he is lowered to the de.
sired depth as quickly as possible.
However. when deep diving is at
tempted. unless the ascent be prop
erly managed and sufficient time al
lowed for the absorbed gases to es-
cape quietly into the blood and thence
into the lungs. where they are ex-
PEELED from the body, minute bubbles
will form in the blood vessels This
bubbling is somewhat similar to that
of a carbonated beverage when the
bottle is opened, except that the gas
which causes the liquid to effervesce
is carbon dioxide, whereas, in caisson
sickness the bubbles are mostly nitro
gen.
1t is when formed in the spinal
lcord or brain that these bubbles are
lmost dangerous. Death. paralysis or
pneumonia often result, while mild