and Vegetation of the Highland Mountains. 319 



Elevation and Temperature of the Highest and Lowest Points 

 - recorded. 



The observations at the upper stations were usually made 

 between 1 and 3 p. m. ; those at the lower preceding or following 

 them by 2 or 3 hours. Notwithstanding this advantage for the 

 upper stations, the decrease of heat appears to be very rapid ; 

 namely, 1° Fahrenheit for 216 feet of elevation. Perhaps the 

 difference of time may be partly compensated by the fact, that 

 ascents were commonly commenced on fine mornings, which 

 were in some instances followed by wet and stormy afternoons. 

 This was particularly the case in Ben Loyal, and the first par- 

 tial ascent of Ben Nevis ; while on Red Cairn and Ben Nevis 

 the second day, the weather was fine, and generally without 

 mist. The mean of the two former gives 1° of temperature for 

 128 feet, that of the two latter only 1° of temperature for 24S 

 feet. Making allowance for the time of day when taken, we 

 should from these details assume the temperature of the month 

 to be thus : — 



Alt. 



1000 feet 

 2000 ... 

 3000 ... 

 4000 ... 



Temp. 



67" 

 52 

 46 

 40 



It is true that these can only be regarded as approximations, 

 but they are worth recording, for comparison with any future 

 observations of a similar kind. The temperature of the small 



