Page:Popular Science Monthly Volume 29.djvu/81

This page has been validated.
PHOTOGRAPHING THE HEAVENS.
71

gether with tea, i. e., a food accessory which is one of the greatest of all retarders of the digestion of starchy food.

The effect of coffee as a retarder of stomach digestion would probably be more felt than it is were it not so constantly the practice to take it only in small quantity after a very large meal; it is then mixed with an immense bulk of food, and its relative percentage proportion rendered insignificant; and to the strong and vigorous the slightly retarding effect on digestion it would then have may be, as Sir W. Roberts suggests, not altogether a disadvantage; but after a spare meal and in persons of feeble digestive power the cup of black coffee would probably exercise a retarding effect on digestion which might prove harmful. It is also worthy of remark that in the great coffee-drinking countries this beverage is made not nearly so strong as with us. In this country good coffee always means strong, often very strong coffee; but on the Continent they possess the faculty of making good coffee which is not necessarily very strong coffee, and which is, therefore, as a beverage, less likely to do harm.

The general conclusion to be drawn from these highly interesting and instructive researches is that most of the "food accessories" which in the course of civilization man has added to his diet are, when taken in moderation, beneficial to him, and conduce to his physical welfare and material happiness; but if taken in excess they may interfere to a serious and harmful degree with the processes of digestion and assimilation. It is also made clear that dietetic habits which may prove agreeable and useful to those who enjoy vigorous health and a strong digestion need to be greatly modified in the case of those who are feeble and dyspeptic.—Nineteenth Century.

PHOTOGRAPHING THE HEAVENS.

By Dr. HERMANN Y. KLEIN.

UNDOUBTEDLY one of the greatest achievements of modern days is the introduction of the exceedingly sensitive dry-plate in photography. By it one is enabled to picture the lightning's flash, the trotting horse, the surging wave, and the foliage swayed by the breeze. It is not to be foreseen what manifold applications this new method will eventually find in the natural sciences. Here we will consider only one of its numerous applications, namely, its use in photographing the starlit heavens.

Whoever has tried to form an idea of the number of stars, visible to the naked eye on a clear winter's night, almost invariably overestimates them. The layman declares he sees a hundred thousand, ay, a million stars. Such estimates, however, far exceed the truth, and, if anything is certain, it is the fact that the number of stars to be seen