40 On Local Attraction. [No. 1, 
crust, which was originally formed by a loss of heat radiated from the 
surface into space, would reduce the heat of the fluid into which it sank, 
and after a time a thicker crust would be formed than before, and the 
difficulty of its being broken through would become greater every time a 
new one was formed. Perhaps the tremendous dislocation of stratified 
rocks in huge masses with which a traveller in the mountains, especially 
in the interior of the Himalaya region, is familiar, may have been brought 
about in this way. The catastrophes, too, which geology seems to teach 
have at certain epochs destroyed whole species of living creatures, may 
have been thus caused, at the same time breaking up the strata in which 
these species had for ages before been deposited as the strata were formed. 
These phenomena must now long have ceased to occur, at any rate on a 
very extensive scale, as Mr. Hopkins’s investigations on Precession appear 
to prove that the crust is very thick, at least 800 or 1,090 miles ; and this 
result has been recently confirmed by Professor W. Thomson in a paper on 
the ‘ Rigidity of the Earth.’”” 
These results meet with some confirmation from an examination of 
the direction of the deflection of the plumb-line at several coast- 
stations where it is drawn towards the sea. The amounts of deflection 
are, however, so small that much cannot be built upon this. This, 
at any rate, may be said, that they present no obstacle to the theory 
so remarkably suggested by the facts brought to light in India, viz. 
that mountain-regions and oceans on a large scale have been produced 
by the contraction of the materials, as the surface of the earth has 
passed from a fluid state to a condition of solidity—the amount of 
contraction beneath the mountain-region having been less than that 
beneath the ordinary surface, and still less than that beneath the 
ocean-bed, by which process the hollows have been produced into 
which the ocean has flowed. These coast-stations do in fact in several 
instances tend directly to favour the theory, as they seem to indicate, 
by excess of attraction towards the sea, that the contraction of the 
crust beneath the ocean has gone on increasing in some instances still 
further since the crust became too thick to be influenced by the 
principles of floatation, and that an additional flow of water into the 
increasing hollow has increased the amount of attraction upon stations 
on its shores. 
Tam, your’s faithfully, 
Calcutta, August 2, 1864. Joun H. Prarz, 


