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Page:Popular Science Monthly Volume 12.djvu/238

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THE POPULAR SCIENCE MONTHLY.

the most natural and the best. If any one will put his faith in recipes, I would remind him of the history of the sale of indulgences. We look back with indignation to Tetzel's scandalous work, but how many people still think they can purchase health by gorging themselves with medicines! Consumptives form no small portion of this class. The treatment here recommended costs no money, but demands only will, self-conquest, and perseverance. The treatment is not so complicated as it may appear; it is simply a movement and an air cure, or, more briefly, an "attempering" cure, for effeminacy is the source of all colds, coughs, and consumption, and hardening is the only protection and remedy against them.—Der gemeinnützige Gesiundheits-Almanach.

 

THE TIDES.
By Professor ELIAS SCHNEIDER.
II.

APART of the theory of the tides presented in our text-books has been pronounced absurd in my first article. It is also a matter of amazement that the effect of centrifugal force is entirely ignored in these text-books. That the propelling force arising from this cause should be utterly disregarded in an explanation of the tides is very remarkable. And yet the existence of such a force is so easily demonstrated that nothing else seems necessary to prove it to be one of the causes of the tides, than what was presented in my first article. I will, however, give additional force to my reasoning by citing the results of actual experiment.

It may be shown that there is an actual difference in the amount of centrifugal force felt at any part of the earth's surface during different times of the twenty-four hours of one axial rotation; and also at different times of the earth's revolution around her centre of motion. Theory implies that when any portion of the earth's surface is moving toward that point in her orbit where such surface makes the most rapid sweep around the centre of motion, the greatest amount of centrifugal force must be felt at such surface; and that, when this part moves toward that point of the earth's orbit where it makes the slowest sweep around the centre of motion, the least amount of centrifugal force must be felt. Now, it is very evident that any portion of the earth's surface which is most remote from the centre of her motion, whether that centre be the sun or the centre of gravity between herself and the moon, makes the most rapid sweep, and that consequently her waters must feel the greatest amount of centrifugal force at that time.