OP THE earth's surface. 153 



lao so completely, that nothing remained of the whole town 

 but a remnant of Fort Santa Cruz. Out of twenty-three ves- 

 sels at anchor in the harbour, nineteen were sunk, and the four 

 others, one of which was a frigate, were carried to a great di- 

 stance on shore, and left on dry land. At Callao, out of four 

 thousand inhabitants, only two hundred were saved. 



Mr Mitchell endeavours to account for this, by his favou- 

 rite doctrine of steam, according to which he conceives, that 

 the strata at the bottom of the sea have been raised as a roof; 

 he then continues, (p. 613.) " now while the roof is raising, the 

 " waters of the ocean, over it, retreat, and flow from thence 

 " every way ; this, however, being brought about slowly, they 

 " will have time to retreat So gently, as to occason no great 

 " disturbance ; but as soon as some part of the roof falls in, the 

 *' cold water contained in its fissures mixing with the steam, 

 *' will immediately produce a vacuum, in the same manner as 

 " the water injected into the cylinder of a steam-engine, and 

 " the earth subsiding, and leaving a hollow place above, the 

 " waters will flow every way towards it, and cause a retreat of 

 *' the sea on all the shores round about." But the gradual 

 elevation of the roof, keeping tight all the while, which is here 

 assumed as the steam was collecting, can by no means be ad- 

 mitted ; since, as we have shewn, a mass such as this, when 

 forced upwards, would have yielded suddenly. 



This phenomenon, however, along with all the rest mention- 

 ed, may, I conceive, be traced as consequences of the simple, 

 but rapid, elevation of the bottom, which we have ascribed to 

 the forcible introduction from below of stone in liquid fusion. 

 Water being almost incompressible, or elastic in an ex- 

 treme degree, it is obvious, that an elevation of that portion 

 of the fluid which lay immediately upon the part of the bot- 

 tom raised, would take place almost simultaneously. This 

 Vol. VII. U elevation 



