VOL. LXXXII.] PHILOSOPHICAL TRANSACTIONS. 201 



mercury sunk, as usual, on his immersion, but to an unusual degree. It did not 

 stop in its fall till it got to 83°, which perhaps might be in part accounted for by 

 the extraordinary chattering of his teeth, admitting some contact of the air. It 

 then mounted in the usual irregular way, and at the end of 13™ had got to 92°. 

 Here it stood for 1 Q"" longer with little variation ; at the end of this time it began 

 to fall rapidly, though irregularly, and in 3™ was down at 85°. He had now 

 been 35"" in the water, and I did not think it safe to detain him longer; we 

 therefore hurried him into a warm bath, heated to 96°, where he shivered much. 

 The bath was heated gradually to 109°, and in this heat he recovered his proper 

 temperature in about aS"*. Being then put into a warm bed, he fell into a pro- 

 fuse perspiration, which left him in his usual health. 



One general remark will serve for the pulse in all these experiments. It was 

 not possible to keep the subjects of them from some degree of previous agitation, 

 and this always quickened the pulse. The natural pulse of Edwards was about 

 70 in the minute; but it may be observed, that it was never slower than 85 

 before immersion, and generally more. However this might be, it invariably 

 sunk to 65, or from that to 68, in the water, became firm, regular, and small. 

 After being long in the bath, it could hardly be felt at the wrist, but the heart 

 pulsated with great steadiness and due force. In the last experiment, when the 

 heat sunk rapidly, Sutton said, that he felt a coldness and faintness at his stomach, 

 which he had not perceived before, and when I felt the motion of his 'heart, it 

 was feeble and languid. In some future trials of the effects of immersion in 

 fresh water, the same coldness at the stomach preceded a rapid fall of the mer- 

 cury ; and these facts, together with the effects I found from applying a con- 

 siderable heat to this part when the body was chilled with cold, convince me that 

 there is some peculiar connection of the stomach, or of the diaphragm, or both, 

 with the process of animal heat. Whoever will consider the rapidity with which 

 a dead body would have cooled immersed in water of the temperature of 40°, may 

 form some estimate of the force with which the process of animal heat must 

 have acted in the experiments already recited. These experiments however fur- 

 nish irrefragable proofs of the futility of some of the theories of animal heat. 

 The increase of heat, in fever, has led some persons to believe that animal heat 

 is produced by, or immediately connected with, the action of the heart and ar- 

 teries; here however it may be observed, that while heat must have been gene- 

 rated in the bath with more than fourfold its usual rapidity, the vibrations of the 

 arterial system were unusually slow. Another, and a very beautiful theory of 

 animal heat, supposes it immediately to depend on respiration; but in the bath, 

 after the first irregular action of the diaphragm from the shock of immersion was 

 over, the breathing became regular, and unusually slow. Lastly, the curious 



VOL. XVII. D D 



