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are. We have had no end of theories as to the formation of the earth. 
We had one theory that it was formed by fusion — that it was the result 
of a fiery mist condensing itself into Plutonic rocks by slow cooling. 
That theory has, however, been abandoned. In the growth of science, 
what were formerly believed to be the oldest rocks are now ascertained 
to be some of the most modern. Even granite is at the present moment, 
in some quarters, doubted to have been of igneous formation, but is con- 
sidered to have been of aqueous formation. We have gone back from the 
Huttonian to the Wernerian theory ; and at the same time Sir Charles 
Lyell tells us, that while the evidences obtained by geologists are throwing 
back the antiquity of man further and further ; that while the , old idea 
we had that all the different strata indicated periods of the earth’s history 
when there was a remarkable uniformity totally unlike the varied fauna we 
see around us now-a layer of one formation, then another layer, and then 
an island lifted up and suddenly, or, perhaps gradually, deposited again — 
that while this theory of gradual upheavals and depressions is still held, it is 
possible that we are getting another swing of the pendulum of geological 
opinion, and that in a few years all this will be abandoned. Sir Charles 
Lyell goes on to show that there has been a certain progress of the science, 
and Professor Morris to-night has told us that mistakes have been made ; 
that there are none of the great gaps which used to be supposed, and that 
that supposition arose from our ignorance. With all this, it is a question 
whether we are not going back very much to what may be called the vulgar 
opinion with regard to the six days’ creation. I say, therefore, that when 
the subject is so beset with difficulties, men of science ought to display the 
Greatest caution. There never was a period when scientific men differed so 
much ; and when, as Lord Bacon has expressed it, men of science adopt 
hypotheses which are to be upheld at all risks, and only accept the facts 
that agree with these hypotheses, then the tendency is to put back t e 
growth of science. We have Sir Charles Lyell himself admitting that the 
theory of successive creations held by him in common with the majority of 
geologists, caused him to shut his eyes to evidence brought before him, 
which he did not admit until he became a convert to Darwin’s theory. 
It is this hypothetical dealing with science of which I complain, because 
I know that it keeps back the truth in most important matters, and 
renders thousands and myriads of observations useless, on account of 
those who made them having been the slaves of theory. Almost all the 
great measurements of crystals which we have in our text-books are not 
the real angles observed ; but the angles, after they have been observed, 
have been changed and twisted and made to correspond with certain notions 
first with regard to molecular formation, and then with regard to the 
proportion of axes. While cultivating all the facts of science, and holding out 
the right hand of fellowship to every man who devotes himself to its cultiva- 
tion, we say be careful of your hypotheses — hold loosely by them. I know 
of no science which is so certain that men should hold strongly by its hypo- 
theses. I think there are but two cases where there is a tolerably exact con- 
