Page:Popular Science Monthly Volume 15.djvu/461

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version. If this be attained, and applied vigilantly and continuously, there is, I have no doubt, far more probability of recovery from an unfortunate inheritance than from an attack of ordinary disease. The chief peril in the latter condition lies in the severity of the struggle, the ground of safety in the former in its mild prolongation, whereby the law of reversion can have unimpeded opportunity through the long and steadfast application of favoring conditions to restore the body to its pristine vigor. The thought may occur that not many have the requisites alleged to be needful for the restoration of defective blood. Yet even this has an outcome not to be deplored. High intelligence, and a will subordinate to it, will survive; while feeble minds and groveling instincts will carry the blood on to overt disease, to untimely death, and to extinction.


WHEN observers band together to watch every quarter of the sky, and to keep on the lookout through the whole night, the number of meteors that present themselves is very great. In this way it has been ascertained that upward of thirty on the average, which are conspicuous enough to be seen without instruments, come within the view of the observers stationed at one locality. And it is computed that telescopic meteors must be about forty or fifty times as numerous as those visible to the naked eye.

These results may be obtained from observations made at one station; but when concerted observations are carried on at different stations several other facts of interest come to light. By simultaneous observations at distant stations, it has been discovered that the height of meteors above the surface of the earth usually ranges from one hundred and twenty down to twenty miles, the average height being about sixty miles; that the direction of their flight is toward the earth, either in a vertical or in a sloping direction; and that their speed in most cases lies between thirty and fifty miles a second.

We thus arrive at the conclusion that visible meteors are phenomena of our own atmosphere; and as the atmosphere reaches a height, at most, of one hundred and fifty miles, and is, therefore, but a thin film over so vast a globe as the earth, it is obvious that the spectators at any one place can see only a very small portion of the meteors which dart about through all parts of this envelope. After making allowance for this, we are forced to conclude that no fewer than 300,000,000

  1. Lecture before the Royal Institution, February 14, 1879.