448 Messrs. L. Hill and M. Greenwood, Jun. [Jan. 16, 



Ohre auf, nur das Gefiihl von Dumpfheit, das Gefiihl eines vermehrten 

 Widerstandes im Ohre, wird in der Mehrzahl der lalle, besonders von 

 Ungewohnten, wahrgenommen." 



We found that all distinct sensations of pressure in the ears were relieved 

 immediately the pump ceased its strokes, and the pressure in the chamber 

 became constant. Our hearing was as acute and, in the opinion of L. H., 

 more acute than normally. The signal of a tap with an iron spanner on 

 the outside of the chamber was, to L. H., painful in its intensity. 



Apart from the feelings of nervousness at being exposed to so high a 

 pressure (which at times were somewhat acute, especially when we were 

 not engaged in analytical work), we could not detect any real sense of 

 pressure, and certainly noticed no abnormality in our bodily functions, with 

 the trifling exception of the voice. Thus during Experiment XV the 

 subject (L. H.) when at -f 60 lbs., wrote : " Very nervous all through 

 experiment ; whenever time for thought, the feelings of pressure, if any, due 

 to non-equilibration of ears when pressure is rising." During the same 

 experiment, when the subject learnt he was at +55 lbs., he wrote : 

 " Thought one was lower until told. No real sense of pressure except lip 

 and voice change." In another experiment, M. G. was nearly two atmos- 

 pheres too low in his estimate of the pressure, while in a third experiment 

 made at a period when custom had lessened the nervous effect, he replied to 

 a question at + 60 lbs., " no sense of pressure." 



The voice changes, observed in all caisson workers, were well marked in 

 ourselves. The alteration is distinct at + 1 atmosphere, and very marked at 

 + 3 atmospheres. The voice has a peculiar nasal and metallic quality, 

 losing the individual characteristics of the speaker. Thus to L. H., when 

 speaking in the chamber, under pressure, his voice appeared like that of 

 M. G. under pressure. So close was the resemblance that L. G. covdd 

 fancy himself outside and listening to M. G. through the telephone. 



At +3 atmospheres the power to whisper or whistle is almost entirely 

 lost. L. H., who retained the power somewhat longer than M. G., could 

 just make an audible whistling note at this pressure. 



This loss of the fine vibratile movements of the tongue and lips, a loss 

 probably resulting from the damping effects of the dense air, leads to a false 

 sense of anaesthesia in the former parts. This conception of anaesthesia is 

 interesting, as being solely excited by a lack of normal movement. 



V. Schrotter and others have laid stress on the diminished frequency of 

 the pulse and lowered blood pressure of caisson workers. Our observations 

 are not sufficiently extensive to permit of any final pronouncement ; but, 

 so far as they go, we are unable to detect any definite change in the pulse 



