Page:Popular Science Monthly Volume 10.djvu/635

Rh so ignorant as he pretends; as others, however, are also asking for explanations, we will consider his most important points.

We had remarked: "A theory is said to be demonstrated when it brings all the known facts into agreement, explains them, excludes all other interpretations, and is consistent with itself and. all that is understood, of the ways of Nature." Dr. Deems asks: "Did Prof. Huxley 'bring all the known facts into agreement?' Did he show that his theory was 'consistent with all that is understood, of the ways of Nature?' Did he not tacitly admit that he was not able to show that his theory was 'in agreement' with what physical astronomy teaches us of the 'ways of Nature?'"

Prof. Huxley certainly made no such admission in any form or degree, and we are at a loss to see how his utterance or the report of it can be so construed. Possibly it is because he dismissed the subject somewhat curtly, which was interpreted into an unwillingness to face it, accompanied by the further inference that he was unable to do so. But it is to be remembered that the question was thrust upon him by editorials in leading newspapers and by private communications, and was not embraced in the plan of his argument, to which he had not half time enough to do justice. He was, therefore, compelled, to be brief; but the case was squarely met. It had been objected that evolution cannot be true because physical astronomy proves that there has not been time enough since the cooling of the earth for the slow processes of life unfolding to have taken place. To this Prof. Huxley replied, first, that he had. already considered the subject in an address before the Geological Society of which he was president, and had showed that the "teachings of physical astronomy" as against geological time are not sound; and he, moreover, knew that this address was accessible to all interested, as it had been circulated by thousands in this country in his volume of "Lay Sermons." Is this to be construed into inability to maintain his theory against the objections raised in the name of physical astronomy?

Secondly, Prof. Huxley replied that, granting the validity of the case made out by the "physical astronomers" (which, of course, he did not grant), even then the biologist has little reason to trouble himself about the result. His proof of evolution comes from another source, and demonstrates to him that there must assuredly have been time enough for its occurrence. It has been customary to affirm that the evolution of life has proceeded at a very slow rate, and required vast periods of time; but what is the basis of the assumption? It is that the series of living forms is distributed through extensive deposits of stratified rocks which the geologist says it has taken vast periods of time to make, and, as the course of life-changes has been coeval with the course of strata-deposition, if the geologist is right, evolution must have been slow. But, if the geologist revises his data either way, the biologist will simply accept the result, and occupy the time. He only says: "There, in the vast succession of rocks, is our proof of evolution as a matter of fact; the geologist and the physicist may settle the question of time between them, and inform us, if they can, how long it has taken." And what is there here of tacit concession that his case was weak as against the "teachings of physical astronomy?"

Let us now briefly examine that case, and see how much occasion for anxiety it gives to the adherents of the doctrine of evolution. "The teachings of physical astronomy" here referred to mean the mathematical and physical speculations of Sir William Thomson in regard to the rate of cooling of the sun and of the earth, the retardation of the earth's rotation by the drag and