THE FREQUENCY OF THE PULSE. 945 



voluntary motion, has been demonstrated by Dr. 

 Knox, who found that in a healthy young man of 

 regular habits, aged 20, the average number of 

 pulsations at 7 in the morning, was 7*4 beats 

 greater than at 10 in the evening, independent of 

 food and exercise. 



horizontal. sitting. standing. 



Average morning pulse .... 62 78'3 90 



Average evening pulse .... 56 67 77 



He has further shown, that the excitability of 

 the heart diminishes regularly from an early hour 

 in the morning until midnight, when it is at zero. 

 And I have found that the mean temperature 

 under the tongue, ceteris paribus, is from 1 to 2 or 

 3 higher early in the morning than at midnight. 



As might naturally be supposed, Dr. Knox ob- 

 served, that the action of the heart was greatly 

 reduced by sitting in a cold room :* that its 

 pulsations are most frequent in infancy, and 

 diminish on till old age, when they are at a 

 minimum : that they are more accelerated by 

 food and exercise in the morning and during the 

 forenoon, than in the afternoon, and least of all 

 in the evening, more in weak than in strong 

 individuals ; but that this does not apply to wine 

 and spirituous liquors : finally, that the action 

 of the heart is augmented more by muscular 

 exertion, than by fever or any other cause. (Ed. 



* Blumenbach says the pulse is slower in cold than in tropical 

 climates, where the mean temperature under the tongue is about 

 2 higher than in England, as shewn by Dr. J. Davy. 



