Lord Kelvin : Animal Thermostat. 199 



temperature of the mouth (as ordinarily taken in medical 

 practice) should be tested every two minutes or so. The tem- 

 perature and quantity and moisture and carbonic acid of the 

 breath should also be measured as accurately as possible. 



P.S., December 5, 1902. — Since the communication of this 

 note my attention has been called to a most interesting paper 

 by Dr. Adair Crawford in the ' Philosophical Transactions ' 

 for 1781 (Button's 'Abridgments/ vol. xv. p. 147;, " Expe- 

 riments on the Power that Animals, when placed in certain 

 Circumstances, possess of producing Cold/'' Dr. Crawford's 

 title expresses perfectly the question to which I desired to call 

 the attention of the British Association ; and, as contributions 

 towards answering it, he describes some very important dis- 

 coveries by experiment in the following passage, which I 

 quote from his paper : — 



" The following experiments were made with a view to 

 determine with greater certainty the causes of the refrige- 

 ration in the above instances *. To discover whether the 

 cold produced by a living animal, placed in air hotter than its 

 body, be not greater than what would be produced by an equal 

 mass of inanimate matter, Dr Crawford took a living and a 

 dead frog, equally moist, and of nearly the same bulk, the 

 former of which was at 67°, the latter at 68°, and laid them 

 on flannel in air which had been raised to 106°. In the 

 course of twenty- five minutes the order of heating was as 

 annexed f . 



Min. 



Air. 



Dead Frog, i Living Frog. 



In 1 



2 



" 3 



,, 4 

 „25 



o 



102 



100 

 100 



95 



O 



70^ m 



72 G8 

 72i 69i 

 73~ 70 



81-1 78 ] , 



" The thermometer being introduced into the stomach, the 

 internal heat of the animals was found to be the same with 

 that at the surface. Hence it appears that the living frog 

 •acquired heat more slowly than the dead one. Its vital 

 powers must therefore have been active in the generation 

 of cold. 



* Observations by Governor Ellis in 1758; teachings of Dr. Oullen 

 prior to 1765 ; very daring* and important experiments bv Dr. Fprdyce on 

 himself in heated rooms, communicated to the Royal Society oi' London 

 in 1774. 



f In the two following- experiments the thermometers were placed in 

 contact with the skin of the animals under the axillae. — Orio. 



