386 Historical 



The friend who accompanied me, who had eaten the same meal 

 as I, had no unusual sensation. (P. 612.) 



Among the conclusions of M. Barella, we shall quote two: 



1. It is best not to go beyond a pressure of three and a half 

 atmospheres above normal pressure. 



2. We may take as a standard of the duration of the decom- 

 pression 10 minutes per atmosphere. 



The others have only a purely medical interest: lymphatism, 

 heart ailments, etc. 



In America, the first bridge constructed by compressed air was 

 over the Great Peedee River, for the railroad from Wilmington to 

 Columbia and Augusta. I have found in my reading no information 

 about this work from the point of view which interests us here. 



In 1869, a truly gigantic work was undertaken at Saint Louis 

 (United States). A bridge with two piers was built over the 

 Mississippi. On the east pier, the depth reached was 33.70 meters 

 below the usual water mark; it was a depth without precedent in 

 the applications of the method, which was to be increased by the 

 occasional floods of the river. The total pressure rose to 4.45 at- 

 mospheres. The total number of workmen employed there was 

 352; about 30 were seriously affected: 12 of these died. 



Here is an extract from the report made by the chief engineer 

 of the work, M. Eads: 30 



When the depth of 60 feet was reached, some of the workmen 

 were affected by muscular paralysis of the lower limbs. It was rarely 

 painful, and went away in two or three days. As the caisson sank 

 deeper, the paralysis went away more slowly. In some cases, the arms 

 were affected, and more rarely the' sphincters and the intestines. The 

 patients also had much pain in the joints when the symptoms were 

 very severe. Nine tenths of the patients felt no pain and got well 

 very quickly. 



The duration of the stay in the air chamber was gradually short- 

 ened from 4 hours to 3, to 2, and finally to 1 hour. The use of 

 galvanic plates or rings seemed, in the opinion of the director of 

 construction and the workmen, to give a remarkable immunity against 

 attacks. Finally, they all had them. They were made of alternate 

 rings of zinc and silver, and placed on the chest, the arms, the elbows, 

 the waist, and under the soles of the feet. The acidity of the perspi- 

 ration was sufficient to establish a galvanic current, and the opinion 

 of those with the greatest experience in these matters was quite 

 favorable to this remedy. Captain Eads is strongly inclined to believe 

 it to be valuable 



The engineers of the port, who very often visited the caisson, 

 have never been ill. 



Physicians have differed greatly about the cause of the symptoms. 



