THE ASTRONOMER-ROYAL OF IRELAND ON EVOLUTION.
THE Royal Astronomer, of Ireland has popularised very effectively the new doctrine as to the great influence of tides on the motions of planetary bodies, like the Earth and the Moon. His Birmingham lecture, published in the numbers of
Nature for November 24th and December 1st, will make a vivid impression on the imagination of thousands of readers who had never understood before how the action of the tides could diminish the length of the day, still less how the action of the tides could, at some former time, have been a force so gigantic that hardly any notion of its primeval magnitude can be drawn .from what it effects at the present day. It is not too much to say that his lecture will mark a great era in the story of .popular science, if, as we suppose, the hypothesis of the throw- ing-off of the moon from the earth, at some period when the rotation of the earth was completed in three hours, instead of twenty-four, and the gradual recession of the moon from the earth since that period to her present distance, be accepted by our modern mathematicians as fairly established by recent mathe- matical researches. If that be granted, no doubt it follows that even since the existence of our oceans in their present form, there must have been a time when the moon was at a distance of only 40,000 miles from the earth, instead. of 240,000 miles, and when,
consequently, the height of the tides must have borne to that of ear present tides the relation of at least 216 to 1, so that the
following picture of their effect, if they could be conceived as .returning to our existing earth, would be what Dr. Ball describes in the following striking passage :-
" To continue our calculation we must take some present tide. Let ns discard the extremes just indicated and take a moderate tide of 3 ft. rise and 3 ft. fall as a type of our present tides. On this supposition what is to be a typical example of a tide raised by the 40,000-mile moon ? If the present tides be 3 ft., and if the early tides be 216 times their present amount, then it is plain that the ancient tides must have been 648 ft. There can be no doubt that in ancient times tides of this amount, and even tides very much larger, must have occurred. I ask the geologists to take account of these facts, and to consider the effect—a tidal rise and fall of 648 ft. twice every day. Dwell for one moment on the sublime spectacle of a tide 648 ft. high, and see what an agent it would be for the perform- ance of geological work ! We are now standing, I suppose, some 500 ft. above the level of the sea. The sea is a good many miles from Birmingham, yet if the rise and fall at the coasts were 648 ft., Birmingham might be as great a seaport as Liverpool. Three- quarters tide would bring the sea into the streets of Birmingham. At high tide there would be about 150 ft. of blue water over our heads: Every house would be covered, and the tops of a few chimneys would alone indicate the site of the town. In a few hours more the whole of this vast flood would have retreated. Not only would it leave England high and dry, but probably the Straits of Dover would be gained, and perhaps even Ireland would in a literal sense become a
member of the United Kingdom. A few hours pass, and the whole of England is again inundated, but only again to be abandoned."
And to such mighty tides Dr. Ball ascribes the grinding down and depositing of what are called the palmozoie rocks,—supposed to be something like twenty miles thick,—up to the top of the Silurian beds. And the Astronomer-Royal of Ireland goes on to explain how the same eausei which have led to the enormous diminution in the magnitude of the tides, as the moon has receded, will lead in the end to a lengthening of the daytill it is as long as the long month of that distant future when the moon and earth will each take 1,400 hours to turn on its axis, and day and month alike will last for more than 58 of our present days. Thus far, as we have said, the Astronomer- Royal of Ireland has admirably popularised and vivified results of modern mathematical research. When he goes on, however, with ponderous and rather deadly-lively jocosity to rallyman on his inability to control these mighty forces, and then taking natural selection as his " comforter," to persuade man that this mighty revolution, when consummated, will be quite consistent with the best interests of mankind, he draws solargely on wholly unscientific assumptions, that lie seems to us to undo a material portion of the good which his lively de- lineation of the significance of recent mathematical investi- gations had done. The following remarks are certainly not worthy of the scientific part of his lecture :— " We beard a great deal a few years ago about the necessity of shortening the hours of labour. I wish to point out that the social reformers who are striving to shorten the hours of labour are pulling one way, while the moon is pulling the other. The moon is increasing the length of the day. The change will be very gradual, but none the less is it inevitable. Where will the nine-hours' movement be when the day has increased to 1,400 hours ? This will be a very serious matter, and there is only one way by which it can be avoided. The question is one rather for engineers than for astronomers ; but I cannot help throwing out a suggestion. My advice -is : Anchor the moon, and keep it from going out. If you can do this, and if you can also provide a brake by which the speed of the moon can be con- trolled, then you will be able for ever to revel in the enjoyment of a twenty-four-hour day. Should this engineering feat never be accom- plished, then we have only the 1,400-hour day to look forward to. Nor is there anything untoward in the prospect, when we take natural selection as our comforter. By natural selection man has becon e exactly harmonised with his present environment. No doubt natural selection moves at a dignified pace, but so in all truth does tidal evolution. Natural selection and tidal evolution have advanced pari passe through all the past millions of geological time. They will advance pari passe through all the ages yet to come. As the day lengthens, so will man's nature gradually change too, without any hardship or inconvenience. All that is necessary is plenty of time. Should wo think it a hardship that our children should have a day of twenty-four hours and one second, instead of twenty-four hours ? That the day enjoyed by our grandchildren should be a second longer than the day of our children ? That the day of our great- grandchildren should be a second longer still, and so on continually? This would be no inconvenience whatever. No one except the astronomers would be able to detect the change, and daily life would be unaltered. Yet, carry on this process for only 150 million years, and we shall find that the whole change of the day from twenty-four hours to 1,44)0 hours has been accomplished. The actual rate of change is indeed much less than this, and is at present so small that astronomers can hardly even detect it. Our remote posterity will have a night 700 hours long, and when the sun rises in the morning 700 hours more will elapse before ho can set. This they will find a most suitable and agreeable arrangement. They will look back at our short periods of rest and short periods of work with mingled curiosity and pity. Perhaps they will even have exhibitions of eccentric individuals able to sleep for eight hours, work for eight hours, and play for eight hours. They will look on such curiosities in the same way as we look on a man who undertakes to walk a thousand miles in a thousand hours." Now, with great deference to the Astronomer-Royal of 'reload, that passage is not only quite unscientific, but approaches very nearly to what we may call buncombe. He had only just shown us how the earth had passed through a stage in which, in con- sequence of one set of physical laws, human life as we know it been quite
at present would have impossible; and not only so,
but that that impossibility must be dated from a past of a duration so inconceivably long, that to our imaginations it may be called infinite ; and further, he had shown us that it had only been by the gradual dwindling of the forces formerly at work,— of the intense heat of the present globe, of the rate at which the earth spun round, of the rate at which the moon spun round, of
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the attraction exerted by the moon on the earth's surface, and of the various large consequences of all these diminutions of inten- sity,—that life such as we know it came to be possible at all. It is to the cumulative effect of various diminutions of intensity in the physical energies at work that he ascribes the comparatively stable equilibrium at which the earth has existed for some ten or twenty thousand years, and will exist probably for another lease equally long, if not longer. And yet he goes on to assume that the indefinite prolongation of these cumulative diminutions of intensity can never land us in another epoch wholly inconsistent with the existence of such life as ours here, but will necessarily accommodate the human constitution to its new conditions, and develope a human nature suited to the altered laws of the planet. Yet the only reason he gives for this assertion is that the length of the day will increase by instalments so minute, that no one generation will be able to recognise a change. He could hardly have given a worse reason. Is it not the very essence of what he has been teaching us that the cumulative effect of small changes is in the end so enormous, that it wholly alters the most essential of the physical conditions of life. Have not such changes, for instance, extinguished the oldest types of terrestrial life altogether, and in the moon extinguished the traces of the very atmosphere itself, without which we cannot conceive of the existence of any type of life in any way allied to our own. Suppose that the accumulation of similar changes in our earth were in the end to extinguish our atmosphere, does Dr. Ball really mean to suggest that the con- stitution of our posterity would be moulded into a form to which an atmosphere would be quite unnecessary ? What can be more irrational than to suppose that if the accumulation of small causes gradually deprived the earth of its vegetation, and therefore also all animal life of its sustenance, the physical constitution of man would gradually assume a form to which neither animal nor vegetable food is necessary ! The argu- ment from analogy requires us to believe that just as it would have been impossible for man to live in the ages when the paimozoic strata were deposited, and the tides were 216 times their present height, so also it would be impos- sible for man to live when the condition of our planet approaches to that of the moon. Though we know that the human constitution is elastic, and that the progress of scientific knowledge tends to make it more elastic, nothing can be less scientific than to assume that this elas- ticity is boundless, and that the steady withdrawal of the present conditions of life would never reach a point at which that elasticity would be exhausted. As it is certain that man could not live back through a reversal of the physical history of the planet, till the time of the glowing mass of red-hot matter returned again, so it is all but certain that he cannot live on till the period of lunar desolation arrives.
if evolution teaches us anything, it teaches us that life, as we know it, is but a short episode in the physical his- tory of the universe ; and that if man has no life which is not indissolubly united with his body, he himself is but a transient phenomenon, of very recent origin, and doomed to what is, speaking in the language of astronomy, very speedy extinction. Even now, nothing can be more untrue than to say that man has become " exactly harmonised with his present environment." Tell that to the countries of great famines, to India, China, or even Ireland ! And yet the change of physical conditions which Dr. Ball pre- dicts will, as regards food alone, be within a thousand centuries infinitely more hostile to man than any physical conditions of which, in human history, man has had ex- perience. How Dr. Ball can seriously maintain that, as the great astronomical changes which he predicts, approach, man's nature will inevitably adapt itself to them, and this too, " without any hardship or inconvenience to himself," the only, condition requisite being " plenty of time," is to us amazing. It had been shown, we thought, sufficiently that the conditions of temperature alone attending on even a day and night such as that of our moon are, in all probability, wholly inconsistent with anything that we call organic life, and much more a day and night of 700 hours each. But the truth is, that Dr. Ball obviously launches into the question with a presumption so violent in favour of all the results of evolution, that he ignores the analogies of the case. For how can any natural analogy suggest that a quite recent result of evolution, which never existed during ages upon ages of past time, is destined to persist through ages upon ages of future time, when we see so many other results of past evolution perfectly ex- tinct? There is some reason to believe that among men of science of the present day, Evolution is thus far taking the place of God, that it is becoming the subject, not of
reasoning, but of acts of faith. Nothing can be more unreason- able. It is reasonable for those who believe in God, and who believe in his infinite love for their feeble race, to expect a destiny worthy of that love. But nothing is more unreasonable than for those who appeal to the law of evolution only, to define in any way to what distant goal it shall lead. They may, judging from experience of the unfolding of the recent past, infer with much probability the course of the near future ; but this is as much as they have any scientific right to do. They possess no pass-key to the workings of a mighty law like that, —a law which has worked for ages when, so far as they know, no rational creature existed, and which, so far as they know, may be destined to work on for ages when every rational creature has ceased to exist. They have, indeed, the key of experience, but that is a key which needs altering with every generation, in order that it may unlock even a few of the secrets of the next genera- tion. Dr. Ball is simply unscientific, when he applies such a key to physical circumstances so absolutely different as those which he anticipates for the earth in time to come. Of course, it would be rash to say that he must be wrong. But it is not rash to say that, judging solely from the probabilities of the case, the argument from analogy, far from being on his side, is entirely against his view. Evolution is not a fit subject for spiritual trust. Those who believe in God should reserve their trust for him, and those who do not believe in God should trust nothing beyond the range of their finite experience.
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