HISTORY OP THE EARTH. 81 
September 20th, 1759. In 177-2 the cone of Papandayang, one 
of the loftiest volcanoes on the island of Java fell in ; a tract six- 
teen miles long by six miles broad was swallowed up, and the 
height of tbe mountain reduced from nine thousand to about five 
thousand feet. 
2. Until very recently, earthquakes were regarded with that 
feeling of interest which is awakened by dread and terror, al- 
most exclusively, and held entitled to notice on account of their 
devastations ; the cities laid in ruins and the lives destroyed by 
them. It is only incidentally that mention is made b}^ the older 
writers of the permanent changes produced by them in the condi- 
tion of the earth itself. 
In June 1819, the country lying about the mouth of the river 
Indus was visited by a violent earthquake. The usual effects 
were seen in the demolition of buildings, especially such as were 
built of stone, and a tract of considerable extent sunk several feet. 
The fort and village of Sindru, standing on the eastern branch of 
the river were so much depressed, that only the tops of the houses 
and wall were visible above the water that immediately flowed 
in from the sea. At the same time another tract of fifty miles 
in length and sixteen in breadth, running past the village at the 
distance of five and a half miles, was elevated into a ridge about 
ten feet in height. In November 1S22, a shock which agitated 
the whole of Chili, raised the line of coast, north and south of 
Valparaiso, through a distance of more than one hundred miles, 
three or four feet, and in the interior of the country the average 
amount of elevation appears to have been still greater. The 
beach of the sea was left bare, and shell fish which adhered to the 
rocks perished. 
HISTORY OF THE EARTH. 
43. Prop. I. The earth was in the beginning a fluid or 
semifluid mass. 
The earth is not a perfect sphere. Its equatorial exceeds its 
polar diameter by about twenty-six miies. (Sec. 6.) This is true 
not only of the terraqueous globe as it exists in oceans, islands 
and continents, but of the great rocky skeleton of the earth. The 
surface of the ground in every country conforms with slight ine- 
qualities to the spheroidal figure which would be assumed by a 
fluid body having the mean density of the earth and revolving 
with the same velocity. As the earth has therefore the form 
which the joint action of gravity and of the centrifugal force pro- 
duced by its diurnal revolution would impress upon it ; we infer 
that its form is the result of the joint action of those forces : and 
as the energy with which it would assume a spheroidal figure is not 
very considerable, we infer that there could have been in the begin- 
ning no rocks of great thickness and solidity to oppose and prevent a 
8 
