282 ITS BEARING ON MEDICAL PRACTICE. 



body, has gained favor among physiological chemists, and also met with 

 acceptance among practical clinical observers. 



Thus the human mind revolves in cycles, and the physicians of the 

 nineteenth century arc preparing to sit at the feet of Moses, and learn 

 that the blood of an animal really constitutes its life; while South Afri- 

 can theologians are disposed to reject his authority, because he happened 

 to confound a rodent with a ruminant.* 



Whatever be the kind of food employed, its effect in the production 

 of force nnist be idtimately measured by the quantities of carbonic acid 

 and water produced by its combustion, and there is no more convenient 

 measure of the production both of carbonic acid and water than urea, 

 so far as it goes. I shall i)rove shortly that every four grains of urea 

 excreted represent five tons lifted through one foot; and I have shown 

 by the preceding investigation that the work represented by urea is not 

 sufficient to account for vital and external work, much less for animal 

 heat. The investigations of Dr. Edward Smith, on the excretion of 

 carbonic acid, enable us to show that the carbonic acid alone is siiflicien: 

 to account for both vital and external work, and also for the production 

 of animal heat. This may be proved as follows: 



Dr. Smith has given results, from which may be deduced the quanti- 

 ties of carbonic acid excreted per minute during the four following 

 conditions: 



1. Lying in the horizontal position, and nearly asleep. 



2. Fasting, and in sitting posture. 



3. Walking at two miles per hour. 



4. Walking at three miles per hour. 



5. Working on the tread-mill, ascending at the rate of 28.C5 feet per 

 minute. 



Carbonic acid per min. 



1. Sleep and rest 5. 522 grains. 



2. Sitting 7. 440 grains. 



3. Walking at two miles per hour J8. 100 grains. 



4. Walking at three miles per hour 25. 830 grains. 



5. Tread-mill 44. 973 grains. 



The foregoing quantities of carbouic acid per minute may be converted 

 into vertical miles i)er hour for the body weight, by multiplying them 

 by the following coefficient :t 



60 X 6 X 8080 X 9 X 772 ^ ^ o'>5'>63 

 22 X 190 X 5280 x 5 x 7000 



log = 2.40420 



*No reasonable person cau fail to perceive tlie ignorance of the great lawgiver who 

 will apply to hi ui the test first proposed by Swift for Homer; Moses, like the author 

 of the Iliad, was ])rofonndly unacquainted with the discipline and doctrines of the 

 Church of England. 



t Dr. Edward Smith's weight was 196 pounds. 



