TRANSACTIONS OF SECTION D. 811 
and flore, taken together, bear somewhat the same proportion to the whole series 
of living beings which have occupied this globe as the existing fauna and flora do 
to them.’ 
Herbert Spencer, in his article on Illogical Geology in the ‘ Universal 
Review ’ for July 1859,' uses these words: ‘ Only the last chapter of the earth’s 
history has come down to us. The many previous chapters, stretching back to a 
time immeasurably remote, have been burnt, and with them all the records of life 
we may presume they contained.’ Indeed, so brief and unimportant does Herbert 
Spencer consider this last chapter to have been that he is puzzled to account for 
‘such evidences of progression as exist’; and finally concludes that they are of no 
significance in relation to the doctrine of evolution, but probably represent the 
succession of forms by which a newly upheaved land would be peopled. He 
argues that the earliest immigrants would be the lower forms of animal and 
vegetable life, and that these would be followed by an irregular succession of 
higher and higher forms, which ‘ would thus simulate the succession presented by 
our own sedimentary series.’ 
We see, then, what these three great writers on evolution thought on this 
subject: they were all convinced that the time during which the geologists con- 
cluded that the fossiliferous rocks had been formed was utterly insufficient to 
account for organic evolution. 
Our object to-day is first to consider the objections raised by physicists against 
the time demanded by the geologist, and still more against its multiplication by 
the student of organic evolution ; secondly, to inquire whether the present state 
of paleontological and zoological knowledge increases or diminishes the weight of 
the threefold opinion quoted above—an opinion formed on far more slender 
evidence than that which is now available. And if we find this opinion sustained, 
it must be considered to have a very important bearing upon the controversy, 
The arguments of the physicists are three :— ’ 
First, the argument from the observed secular change in the length of the day 
the most important element of which is due to tidal retardation. It has been 
known for a very long time that the tides are slowly increasing the length of our 
day. Huxley explains the reason with his usual lucidity: ‘That this must be so 
is obvious, if one considers, roughly, that the tides result from the pull which 
the sun and the moon exert upon the sea, causing it to act as a sort of break upon 
the solid earth.’ ” 
A liquid earth takes a shape which follows from its rate of revolution, and 
from which, therefore, its rate of revolution can be calculated. 
The liquid earth consolidated in the form it last assumed, and this shape has 
persisted until now, and informs us of the rate of revolution at the time of con- 
solidation. Comparing this with the present rate, and knowing the amount of 
lengthening in a given time due to tidal friction, we can calculate the date of 
consolidation as certainly less than 1000 million years ago, 
This argument is fallacious, as many mathematicians have shown. The present 
shape tells us nothing of the length of the day at the date of consolidation ; for 
the earth, even when solid, will alter its form when exposed for a long time to the 
action of great forces. As Professor Perry said in a letter to Professor Tait: % 
‘T know that solid rock is not like cobbler’s wax, but 1000 million years is a very 
long time, and the forces are great.’ Furthermore, we know that the earth is always 
altering its shape, and that whole coast-lines are slowly rising or falling, and that 
this has been true, at any rate, during the formation of the stratified rocks. 
This argument is dead and gone. Weare, indeed, tempted to wonder that the 
' Reprinted in his Essays, 1868, vol. i. pp. 324-376. 
2 Anniv. Address to Geol. Soc., 1869. » Nature, Jan. 3, 1895. 
‘ It must not be forgotten, however, that this argument and those which follow it 
- have done very good work in modifying the unreasonable demands of geologists a 
quarter of a century ago, 
3G2 
