1853.] OF THE ROYAL INSTITUTION. 287 
to the data before laid down, upwards of two million years to 
achieve. 
One inducement to call attention to such calculations is the hope of 
interesting engineers in making accurate measurement of the 
quantity of water and mud discharged by such rivers as the 
Ganges, Brahmapootra, Indus, and Mississippi, and to lead geologists 
to ascertain the number of cubic feet of solid matter, which ancient 
fluviatile formations, such as the coal-measures, with their associated 
marine strata, may contain. Sir Charles anticipates that the chro- 
nological results, derived from such sources, will be in harmony 
with the conclusions to which botanical and zoological considerations 
alone might lead us, and that the lapse of years will be found to be 
so vast as to have an important bearing on our reasonings in every 
department of geological science. 
A question may be raised, how far the co-operation of the sea 
in the deposition of the Carboniferous Series might accelerate the 
process above considered. The Lecturer conceives that the inter- 
vention of the sea would not afford such favourable conditions for 
the speedy accumulation of a large body of sediment within a 
limited area, as would be obtained by the hypothesis before stated, 
namely, that of a great river entering a bay in which the waves, 
currents, and tides of the ocean should exert only a moderate degree 
of denuding and dispersing power. 
An eminent writer, when criticizing, in 1830, Sir Charles Lyell’s 
work on the adequacy of existing causes, was at pains to assure 
his readers, that while he questioned the soundness of the doctrine he 
by no means grudged any one the appropriation of as much as he 
pleased of that. “least valuable of all things, past time.” But Sir 
Charles believes, notwithstanding the admission so often made in the 
abstract of the indefinite extent of past time, that there is practically 
speaking a rooted and perhaps unconscious reluctance on the part 
of most geologists to follow out to their legitimate consequences the 
proofs daily increasing in number of this immensity of time. It 
would therefore be of no small moment could we obtain even an 
approach to some positive measure of the number of centuries 
which any great operation of nature such as the accumulation of a 
delta or fluviatile deposit of- great magnitude may require, inasmuch 
as our conceptions of the energy of aqueous or igneous causes or 
of the powers of vitality in any given geological period must depend 
on the quantity of time assigned for their development. 
Thus, for example, geologists will not deny that a vertical sub- 
sidence of three miles took place gradually at the South Joggins, 
during the carboniferous epoch, the lowest beds of the Coal of Nova 
Scotia like the middle and uppermost consisting of shallow-water 
beds. If then this depression was brought about in the course of 
375,000 years it did not exceed the rate of four feet in a century, 
resembling that now experienced in certain countries where whether 
the movement be upward or downward it is quite insensible to 
