624 
Proceedings of Royal Society of Edinburgh. [sess. 
from 10*19 at 7a to 17*11 inches at 5a, the latter being the heaviest 
monthly rainfall recorded in the period under review. 
The rainfall in the different months is shown in the appended 
tables Nos. 2 and 3. Table No. 2 is made up by selecting 
respectively the highest and lowest individual readings ob- 
tained. Table No. 3 is made up on the basis of the average of 
all the gauges. 
The average 
under : — 
annual rainfall 
at the different 
gauges is 
No. 1 
56*23 
No. 5a 
73*92 
„ 2 . 
65*53 
„ 6a . 
61 43 
„ 3 . 
66*02 
5, 7a 
47-66 
„ 4 . 
66*81 
The highest rainfall in any one year recorded at a particular 
gauge was 89*88 in 1897 at gauge No. 5a, and the lowest was 
36*37 in 1902 at gauge 7a. 
The only fact which seems to be established as the result of the 
gaugings is that station 5a is the wettest from every point of view. 
It had the heaviest daily, monthly, and annual rainfall, and the 
largest total rainfall, and station 7a is the driest station. 
It would seem therefore that the ordinary rule that prevails, 
viz., that rainfall increases by 2 or 2J per cent, for each 100 feet 
of ascent, can only be accepted with considerable modifications, and 
that a great deal must depend on the direction and nature of the 
prevailing winds, and on the exposure of the gauges. 
The lowest gauge is No. 6a, which is at a height of 966 feet, and 
shows an average rainfall of 61*43, while the highest gauge, No. 2, 
at a height of 2627 feet, has an average annual rainfall of 65*53, 
or an increase of only 0*41 per cent, per hundred feet of rise, and 
gauge No. 5a, with a height of 1537 feet, has an average rainfall 
of 73*92, equal to an increase of 3*56 per cent, per hundred feet 
of rise. 
The annexed diagram shows by circles the average annual 
rainfall recorded at each of the gauges, and by dotted line the 
rainfall that might have been expected at each of the gauges, 
taking the rainfall at the lowest gauge as a basis, and adding 2J 
per cent, per hundred feet of rise to the others. 
