1000 ft in a million Years,

Otago Witness, Issue 1916, 10 August 1888, Page 32

1000 ft in a million Years,

and in the many millions of years which no doubt belong to the earth's future, every trace of water would disappear. The earth, if such a change . took place, might still bo the abode of some forms of life. It delights some who regard themselves as exceptionally philosophic to dwell upon the possibility that there may be some forms of life even in the airless and waterless moon. For my own part, I think that we might as reasonably grow enthusiastic over the possibilities of other forms of life in a dead carcass besides the life which it originally possessed, as dwell upon the possible forms of life which may exist now upon the moon, or might exist hereafter upon the earth if she became an airless and waterless world ike her companion planet. For all life interest she could have for us, the earth would be absolutely dead if she were deprived of all the waters which now clothe her surface. I have just touched upon the airless condition of the moon. A planet may die as completely by the diminution of its atmosphere as by the disappearance of its waters. One or other process may be the firsi. to atl am life- destructive degree; or the two may advance pan jhissu. But iv considering ihe death of a planet we must take each separately into account. Now, although men may recognise no change in the condition of the earth's atmosphere iv hundreds or even in thousands of years, it is ceitain that in the past millions of years during which our caith lias been the abode of life, and still more during the preceding tons of millions of years of her iicry youth, her atmospheric envelope has been steadily diminishing in

density. "" Gases 'md vapours which formerly were present in large quantities in the terrestrial atmosphere are now only found in relatively minute quantities, except in the neighbourhood of active volcanoes. The gases themselves which constitute the air as it now exists must be diminishing, though imperceptibly during periods so short as the lives of individual men. For processes are continually going on by which both oxygen and nitrogen are abstracted from the air, to be returned only in part by later chemical changes. In ihe course of millions of years the oir will be perceptibly diminished in density ; and although it may be very doubtful whether life on the earth will ever be seriously affected in this way, that is only bacause life will probably be destroyed in other ways, long before thi3 particular change will reach a destructive degree. In some among other worlds than ours the case may be otherwise, and this change may be the one by which life of the higher orders is first brought to an end. Of course in considering all such changes as these, which operate so slowly that millions of years have to be taken into account, we must remember