Page:Popular Science Monthly Volume 39.djvu/629

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GLASS-MAKING.

GLASS-MAKING.

V. GLASS IN SCIENCE.

By C. HANFORD HENDERSON,

PROFESSOR OF PHYSICS AND CHEMISTRY IN THE PHILADELPHIA MANUAL TRAINING SCHOOL.

WHEN we compare the modern man, the product of many-centuries of more or less continuous culture, with the men of ancient Rome, and still more with the men of ancient Greece, the impression unwillingly forces itself upon us that man has somewhat deteriorated since the days of Carthage and Thermopylæ. The reflection is a discouraging one. But observe how unavoidable it is. The modern man can not run so far or so fast, can not see so well, hear so acutely, or speak so loud. All his direct physical powers have suffered diminution. If the comparison be extended to the intellectual world, it is clearly manifest that the loss of power in one direction has not been compensated by the gain in another. One need have no great turn for Hellenism to perceive that the average American, despite his boasting, appears but a struggling child beside the heroes of either the Olympian games or the Athenian groves.

The effect of such a comparison as this is to make one question the truth of human evolution, and to ask himself in all seriousness whether the history of the race is not one of retrogression rather than of advance. But there is another way of looking at the matter, and there are other factors which must needs be taken into consideration.

The suggestion, I believe, is due to Mr. Spencer that, in attempting to measure man's physical power, the summary should not be limited to his direct faculties, but should justly include the acquisitions gained through the exercise of his intelligence. Thus, while it is perfectly true that modern legs are not so sturdy as Grecian legs, it must not be forgotten that by means of steamer and railway the modern man can girdle the earth in a couple of months, and can travel almost unlimited distances at the rate of fifty miles an hour. At the present moment popular lecturers are demonstrating that there is no reason why he should not go two and a half miles a minute. Since this facility of movement is the product of his own increasing development, we must admit that a longer view establishes an increased power of locomotion in the history of the race, and that even here evolution has been constant. The modern vision is faulty and astigmatic. We are veritable bats compared to the men of antiquity, or even to the modern American Indian. But here, again, the brain has more than compensated the defects of the eye. By means of the micro-