33 ° 
Scepticism in Geology. [June, 
than a mile, flowing along an undulatory plain bounded by 
distant hills, on a sudden drops down into a crack stretching 
direCtly across its course, forming a trough 350 feet deep, 
but not more than 80 feet wide, into which the whole body 
of water is discharged. The Fall is twice as high and twice 
as wide as Niagara, but differs from it in that, immediately 
opposite the Fall, rise three successive natural walls of rock 
of the same height as that over which the river leaps, sepa- 
rated from one another by narrow rifts. These triple barriers 
consist of wedge-shaped promontories of rock, with vertical 
sides, projecting alternately from the right bank and from 
the left, like side-scenes in a theatre, but entirely overlapping 
one another. Out of the first deep trough the river, after 
its descent, is compelled to find its way through a gap only 
80 yards wide in the first opposing rock wall. A second 
wall here confronts it, by which the stream is turned at an 
acute angle to the right. It is next forced round the second 
promontory, then reversing its course round a third, and 
before it is allowed to escape to the sea it is compelled to 
double round a fourth wider headland.” 
“ Verifier ” forcibly argues that no aCtion or application 
of running water could cause a river of first magnitude, 
flowing over a flat surface of rock, thus suddenly to drop 
into the bowels of the Earth. The surging river is obviously 
confined and governed in its course by the remarkable fissure 
through which it has to pass ; but when ‘‘Verifier” suggests 
that the fissure was possibly the result of “ some shrinkage 
of the basaltic rock, when cooling down from an incandescent 
state,” he certainly does not offer a more probable origin 
than may be found in the known effects produced by earth- 
quakes or the suggested results of subterranean movements. 
It is a favourite idea with some geologists and astronomers 
that certain phenomena are to be accounted for by the con- 
traction or shrinkage of the Earth's crust consequent upon 
the radiation of heat ; and yet the sedimentary rocks of 
which it is largely composed supply no evidence to justify 
the conclusion that in former ages they were subjected to a 
temperature greatly different from the present. Recent ex- 
periments, moreover, by Herren Nies and Winkelmann, 
show that the common idea as to the expansion of bodies 
by heat and their contraction on cooling (with the notable 
exception of ice) is erroneous. It has been found that silver, 
tin, zinc, iron, copper, bismuth, and antimony all expand 
when taking the solid form. The effeCt upon some of the 
other metals has not been clearly ascertained ; but, as in the 
well-known case of ice, careful experiments justify the con- 
