34§ 
Mr. Playfair’s Account of a 
which, though it be nearly a medium when stones of every 
kind, from the lightest to the heaviest, are included, is cer- 
tainly too small for Schehallien, the rocks of which belong to 
a class of a specific gravity considerably above the mean. 
The uncertainty arising from this source might not be of great 
amount, yet it was desirable that the quantity, or, at least, the 
limits of it should be accurately ascertained. In this light I 
knew, from repeated conversations, that the matter was re- 
garded by both the gentlemen above named. 
I had therefore long wished to attempt such a survey of 
the mountain as might afford a satisfactory solution of this 
difficulty; and having mentioned the circumstances to the 
Right Hon. Lord Webb Seymour, he entered readily into a 
scheme, which without the assistance of his skill and activity, 
I should have been quite unable to carry into execution. 
Accordingly, in June 1801, we took up our residence in a 
small village as near as we could to the bottom of the moun- 
tain, and began our Mineralogical Survey, the result of which 
we think it our duty to submit to the Society, under the 
auspices of which the original experiment was undertaken. 
It was obvious, that our first object must be to obtain speci- 
mens of all the varieties of rock in the mountain, which had 
any considerable difference in their external characters. These 
specimens must be such as had not been exposed to the ac- 
tion of the weather, were perfectly sound, with a fresh fracture, 
and taken from the living rock. In order to procure these, 
we soon found that it was not necessary to dig into the 
mountain or to blast the stones with gun-powder, for the 
native rock breaks out on the bare and rugged surface in 
abundance of places, and is so deeply intersected by the 
