SOME PHENOMENA OF COMPRESSED AIR 

 IN RELATION TO ORGANIC LIFE. 



RY THOMAS B. WHITNEY. * 



The purpose of this paper is to describe some of the phe- 

 nomena of air under high pressure, in relation to animal and 

 plant life. 



There is some question as to the date when compressed air 

 was first employed in submarine work, and in sinking caissons 

 through water bearing strata for foundations, etc., but in 1839 

 it was used in France, on a considerable scale, to reach a 

 seam of coal under the River Loire, a caisson being sunk 

 through the river bed. It has long been used in operations of 

 divers working in suits and in diving bells, though the latter 

 appliance is now but little used. 



Of recent years it has been employed upon a very exten- 

 sive scale, on three great works of construction in the United 

 States — the St. Louis Bridge, the Brooklyn Bridge, and the 

 system of subaqueous tunnels now approaching completion 

 under the waters of New York harbor. While engaged upon 

 the latter work, the writer passed some thousands of hours 

 under varying degrees of atmospheric pressure, and had an 

 opportunity to note some phenomena which may be of interest 

 to the Institute. 



The gauges used upon caissons and tunnel locks read zero 

 in normal air, so that all pressure is recorded in pounds to the 

 square inch, above normal. Thus a reading of 20 pounds 

 means 20 pounds above normal air pressure. The number of 

 atmospheres in the caisson or tunnel heading therefore ^ one 

 atmosphere -f gauge reading. 



In laying the pier foundations of the St. Louis Bridge the 

 pressure under which work was carried on exceeded -|^ 50 

 pounds to the square inch, or somewhat more than four atmos- 



*Mr. Whitney was an inspector of shield driving and work on the 

 Penna. R. R. tnnnels nnder the Hudson River for one and a half years. 



