136 
EXTRACTS—NATURAL HISTORY. 
by the hypothenuse with that perpendicular, we can have no difficulty in cor¬ 
rectly ascertaining the length of the base. 14. The length of the base is the 
exact amount of space destroyed by the action of the waves, since the chalk 
first became dry land. 15. The length of the base being ascertained, and also 
the rate of decay per annum, we are led with certainty to the number of years 
which have elapsed since the erosive action first commenced. 16. As this action 
is unceasing, and as the chalk is peculiarly affected by it, it never could have 
been in full force, even for a single century, without occasioning a cliff. 17 As 
no such cliffs exist, from top to bottom of the whole chalk formation, except 
those now in progress on the shores, the sea never could have acted upon the 
chalk for any length of time, except on' its present level, as compared with the 
chalk. 18. We are thus forced to the conclusion, that to whatever elevation the 
chalk may extend, and it is upwards of 1000 feet in England, the whole mass 
was either raised at one time from the bosom of the deep, or the deep was 
depressed, at the same individual period, so far below its former level. 19. No 
stratum now reposing on the chalk above the level of the sea, could have been 
deposited in the sea since the present cliffs were begun. 20. The whole series, 
therefore, what are usually termed Tertiary Strata, reposing on the chalk, were 
formed in the sea previous to the elevation of the chalk, and were elevated along 
with it at the very same period. 21. Assuming 900 yards as the mean extent of 
decay of the chalk coasts of both sides of the British channel, (as indicated in 
the thirteenth position,) a waste of eight inches per annum gives four thousand 
years as the age of the chalk as a dry land. 22. As eight inches are above the 
general average decay of chalk cliffs at their present height, so it must have been 
greatly below the real amount during the first two thousand years of the opera¬ 
tion, and may be considered as a fair general average of the whole. 23. As the 
action of the Falls of Niagara in the midst of the great marine formation of 
North America, brings us exactly to the same period of about four thousand 
years; as we are, in neither case, able to extend the calculation much beyond 
that period ; and as both coincide so exactly with what Sacred History and the 
traditions of all nations have handed down to us, we may look upon these 
latter as being most fully confirmed, as to the great and preternatural event to 
which they both bear witness. 24. As we know of no law of nature by which 
the chalk formation, and the tertiary strata reposing upon it, could have been 
raised, at one time, above their native element, we must conclude that this effect 
was the result of a preternatural power, and of an Almighty decree. 25. We are 
thus forced to admit a more powerful agent into our systems of geology than the 
mere laws of nature, to which all phenomena are generally referred ; and the 
science is thus placed upon a new, a more solid, and more consistent founda¬ 
tion .—To be continued. 
M. Boit on the Sap of Plants. —The sap received at the roots evaporates 
by the leaves, whilst between these points the vegetable tissue acts precisely as a 
cylinder, composed of animal charcoal, covered with an impenetrable envelope, 
and with its lower part immersed in liquid. The column is thus supplied with 
all the liquid that it can contain ; the vegetable tissue becomes itself in the state 
of saturation that suits its mass under the existing temperature. This kind of 
equilibrium being established, should any cause, a sudden change of tempera¬ 
ture for instance, increase the evaporation at the extremity of the branches, 
these will act by suction ; draw more from the roots, and the equilibrium is still 
