various Altitudes, in connexion ivith the act of Ascending. 331 



after (say a minute later), while I continued walking. The 

 temperature, I conclude, was steady when first observed, as I 

 could read it several times over without its altering; and the 

 rising which took place a minute or two later was rapid, and 

 would not have allowed of two similar readings being taken in 

 succession. I explain this by assuming that, with the object of 

 observing correctly the degrees of the thermometer, I was neces- 

 sarily compelled to slacken my speed a little, thereby allowing 

 heat to be formed afresh by the body to make up for that which 

 had been used in excess in the act of climbing. 



I made a rule, with every observation, to note the time 

 when food had been last taken, and observed that walking 

 up hill fasting cools the body to a greater degree than it does 

 after taking food, or while digestion is going on. Thus on arri- 

 ving at the " Pierre a Pechelle," 2060 metres, while in the act of 

 ascending my temperature was 36° # 5, and shortly after 36°-8. 

 I made two excursions from Chamounix, with the object of 

 determining the influence of food on the temperature of the body 

 while going up hill. About an hour's climbing on the Bre- 

 vent takes the tourist to a hut called the " Chalet des Cha- 

 blettes/' I left Chamounix about an hour and a half after a 

 plentiful breakfast and while digestion was still going on ; about 

 a quarter of an hour before arriving at the chalet, and without 

 slackening my speed, I ascertained my temperature under the 

 tongue to be steady at 36°*5 after four minutes' exposure ; and 

 on walking slower, after having noted this result, the temperature 

 rose to 37°. On one of the following days, I left Chamounix 

 for the Chalet des Chablettes early in the morning before break- 

 fast, and consequently having taken no food whatever since the 

 previous evening. About a quarter of an hour before arriving 

 at the chalet, and while keeping up the speed of ascent, I ascer- 

 tained my temperature to be35°*3, the bulb of the thermometer 

 having been kept for six minutes under my tongue. The heat of 

 the body in this last experiment, or while ascending with an empty 

 stomach, was therefore 1°'2 less than in the previous experiment, 

 when food had been taken. After showing 35°*3 in this last 

 experiment, the thermometer rose rapidly, probably because I did 

 not walk up quite so fast as I had done before reading the 

 instrument; and on arriving at the chalet it was up to 36°*4. 



I have thought it best to report my observations in the form 

 of Tables, which are appended to this communication ; the results 

 obtained are as follows. 



Result I. — That the temperature of the body, in the state of rest, 

 does not, as a rule, appear to fall at increasing altitudes above 

 the sea, and consequently a lessening of the atmospheric pressure 



Z2 



