106 Aqueous Vapour Atmosphere. 
the salubrious air of the mountains and lakes 
near my native place in the North of England; 
it was therefore an additional gratification to 
be enabled to unite instruction with amuse- 
ment.—I began my observations relative to 
this point in 1803, and have continued them 
almost in every successive year to the present. 
The principal mountain on which the ob- 
servations were made was Helvellyn, on the 
confines of Cumberland and Westmoreland; 
but most or all of the other high mountains — 
in the vicinity have occasionally served my 
purpose. Helvellyn is the highest mountain 
of a long range running nearly from N. to 8. 
for eight or ten miles. The high road passes 
close upon the foot of it. The ascent for the 
first half is very steep, for the last half it is 
a pleasant gradual slope. The mountain is 
mostly covered with a dry green turf, but 
there are several huge rocks and precipices, 
and in places many beds of loose stones. A 
copious stream of water, collected from se- 
veral fine springs in the upper part of the 
mountain, descends the west side of it, in 
rainy seasons forming an almost continuous 
series of cascades, which has a fine appear- 
ance from the valley.—I have had a portable 
barometer not less than seven times upon the 
summit, and can fully answer for the accu- 
