THE "BEND" ON THE BATTLEFIELD.

Waikato Times, Volume 87, Issue 13275, 2 September 1916, Page 4 (Supplement)

THE "BEND" ON THE BATTLEFIELD.

Many of the soldiers killed by highex plosive shells in the present war meet tie i,- death, not from wounds, nor from nervous shock, but from identically the same disease that affects men who have* been working under high air pressure. This disease, variously known as "the

bends" or "caisson-disease,"' is duo. not

to the pressure itself, but to its too sudden release. When the worker comes out into the open air his blood fills with bubbles like an uncorked soda or cham-pagne-bottle, and if these are large enough to dog ihe circulation be dies at once. On the battle-field, both the increase of pressure and its sudden release are due to the passage of -an intense explosion wave. The whole effect takes place in a fraction of a second, mid the man dies where he stands, sits, or lies, without changing his position. How the real cause of this phenomenon was discovered by the adventure of a pocket aneroid barometer is told in an article on "Death, by Decompression," contributed to La Nature (Paris, December 18). Says the writer, in substance: "After each of the recent battles, it lia.s been shown that although most of the corpses bore traces of projectiles, there were others without apparent wounds that preserved the attitude in which they were at the moment of death. It: was generally admitted that these died of shock, from an instantaneous stoppage of the circulation ; but no further explanation was possible. This was the state of affairs when M. Arnoux told a meeting of the French Society of Engineers how a French officer at the front had found a pocket aneroid barometer which had been put out of coinmission bv the near-by explosion of a German shell. Its stoppage was found to be due to the fact that one of the levers for transmitting the movements of the aneroid box to the pointer, which normally rest on the other lever, had Passed beneath it. This could only have been due to abnormal inflation of the box, caused by considerable barometric depression. "The two levers were replaced in normal position, and the machine was placed under the bell of an air-pump. My lowering the pressure little by little, the experimenter showed that one lever slipped under the other when it reached a degree of exhaustion about equal to that at the top of Mont Blanc at ail elevation of I 0,000 feet. "We may logically conclude, then, that the explosion of the shell caused a brie) barometer depression corresponding to the pushing back of the air at a rate of about 900 feet per second. Under such a pressure all near-by objects are thrown down and all living things being physiologically destroyed by the violent displacement of the air, while those sheltered behind any obstacle can be affected only by the static lowering of pressure iu the surrounding atmosphere.

"Xow, the effects of lowering the barometric pressure have been observed in aeronautics, when a too-rapid ascent lias occasionally been fatal. We know that the blood holds in solution air and •ai'bonie acid, in larger proportion as :he pressure is higher, and that these ia.ses separate out as bubbles when soda

wafer or champagne is opened. In this case ihe bubbles escape from the bottle, but in the human body they are caught mi the eapilk iries, where they stop the circulation of blood instantly. "The phenomenon is dangerous onlv when the lowering of pressure is vcrv sudden, tor the bubbles are dangerous only when they are large enough to obstruct the capillaries. Death is said to occur from 'gaseous embolism.'

"Hip i'll'ects produced by shell-explo-sion have thus been long familiar in other fields. Observed in aeronautics, they are also known amonsj workmen engaged in tunnelling. Working at depths of i ■; to 100 teet, and thus subjected to pressure? of to 3 atmospheres, their return to normal pressures must take place very slowly, to enable the <ras in theblood to escape in small bubbles.