MEMOIR OF DR. WALKER. 
31 
to think that we had now the altitude of the moun- 
tain with as great exactness as it could he taken by 
the barometer. 
“ We at the same time put the thermometer into 
boiling water, and after repeated immersions, it was 
observed to stand constantly at two hundred and 
thirteen degrees. The thermometer employed was 
one constructed by Professor Wilson at Glasgow, 
and we were therefore assured of its accuracy. The 
water carried to the top of the mountain was from 
a pure perennial spring on the shore of J ura ; and 
the water of the same fountain was employed in 
the repetition of the experiment. 
“ From these experiments, therefore, it appears 
that a column of air of the height of this mountain 
is equal to two inches and six-tenths of mercury. 
And assuming Dr. Halley’s calculation of ninety 
feet for each tenth, the perpendicular height of the 
mountain turns out to be 2340 English feet above 
the surface of the sea, which is just three hundred 
feet less than half a measured mile. 
“ The difference of the heat of boiling water, at 
the summit and at the bottom, appears from these 
experiments to be equal to six degrees of Fahren- 
heit’s thermometer; and tho height of the moun- 
tain, divided by this number, gives three hundred 
and ninety feet for each degree." 
The following is the Report which he made to 
the Society for propagating Christian Knowledge, 
concerning the state of the charity schools in the 
Highlands and Islands. 
