452 



in the quiet sitting posture during five minutes at the commencement 

 of each quarter of an hour from 5 A.M. to 6^ P.M., and of each half- 

 hour from 6i P.M. to 3 A.M. Exercise was taken in the intervals, 

 and food was eaten at 8 A.M., 1, 5, and 8 P.M. 2ndly, by using 

 the spirometer without intermission during the whole of the 24 hours, 

 except at intervals amounting collectively to 40 minutes. The pos- 

 ture, exercise, and periods of sleep were noticed and recorded, and 

 the quantity of air inspired was read off at the end of every five 

 minutes. Srdly, by an inquiry similar to the second, but continued 

 through the night only, from 6f P.M. to 5f A.M. ; the quantity being 

 recorded every quarter of an hour. The first inquiry was made on 

 July 7 and 8, 1856, the second on January 19 and 20, 1857, and 

 the third on January 21, 1857. 



The maximum influence of various agents was determined both by 

 the quantity of air inspired taken absolutely, and also relatively to 

 that recorded immediately before the influence in question was 

 exerted. The inquiries were made before breakfast, or at periods 

 distant at least three hours from the last meal, so as to avoid the 

 disturbing influence of food. Exertion, variation of posture, mental 

 inquietude, change of temperature, &c., were avoided during the 

 continuance of each inquiry, and hence the observations were never 

 continued beyond a period of two hours. The quantity of air was 

 determined during periods of five minutes at a time, twice during the 

 first quarter of an hour, and once at the commencement of each suc- 

 ceeding quarter of an hour. The results were averaged per minute. 



In all the above-mentioned inquiries the rate of respiration and 

 pulsation and the temperature of the wet and dry bulbs with the 

 barometric pressure were recorded. 



The temperature of the breath was determined by the aid of an 

 instrument consisting of a boxwood tube %. of an inch in diameter and 

 1 inch in length, through the sides of which and at a right angle 

 to it, a small thermometer was inserted and the bulb exposed freely 

 to the exhaled breath. A valve was placed at the distal end which 

 permitted the exit of the breath, but prevented the entrance of 

 air, whilst near to the end which was placed between the lips when 

 in use, a valve was fixed which moved in both directions. The bulb 

 of the thermometer was thus enclosed in a small chamber. 



The paper concludes with a summary of the principal results ob- 



