12 Memoirs of the Life and Works’ - : 
latitude and longitude of Greenwich. Dr. Maskelyne, to 
whom the memoir was sent, showed with his eloquence 
and usual moderation, that the doubts were without founda- 
tion; but he did not oppose the means used by others to 
remove them. On this occasion the English, who had at 
that time done little in the way of great geographical ope- 
rations, in which the French had distinguished themselves, 
in their turn became eminent, and surpassed all that had 
hitherto been done. At this time also MM. Cassini and 
Legendre made trial of the circle of Borda. 
Bouguer, at the conclusion of his measure of the degree 
in Peru, had attempted to determine the attraction of 
mountains, by the quantity which the plumb-line of the 
astronomical sector was affected. He found a sensible at- 
traction, but it was only half the quantity it should have 
been from the size of the mountains hence he conclude! 
it must be hollow, and internally mined with volcanoes: 
The result, from the incorrectness of his instruments, was 
not to be depended on. Bouguer had himself expressed a 
wish that the experiment should be made again in Europe, 
with better instruments. Dr. Maskelyne undertook this 
with the sector he had at St. Helena, but of which he had 
corrected the suspension, and changed the divisions. He 
made choice of the mountain of Schehallion in Scotland. 
In his account wil! be seen the care and trouble this work, 
which appears so easy, cost him. He found 5:8 for the 
quantity the line was affected by the attraction of the 
mountain; from thence he concluded the density of the 
mountain was the mean density of the earth: the result 
deduced was, that the density of the earth is greater towards 
the centre than at the surface, which has been also proved 
by the measure of degrees, and by the pendulum : in fact, 
the density of land is four or five times greater than that 
of water. Cavendish, by experiments of another kind, has- 
found five and a half; but he had some doubts of the cor- 
rectness of his own conclusion ; and as that of Maskelyne 
is also established on some circumstances necessarily sub- 
ject to some degree of uncertainty, we may, until we have 
further experiments, take the density of the earth at very 
near five times that of water. In short, Dr. Maskelyne 
admits it as very possible, that the unequal density of the 
surface may have occasioned the difference in the several 
degrees which have been measured. 7 
These are the principal works published by Dr. Maske- 
lyne; he has left many others which have not yet appeared, 
and the learned will undoubtedly hear with pleasure, that 
the 
