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Page:Popular Science Monthly Volume 6.djvu/754

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THE POPULAR SCIENCE MONTHLY.

is much the same as that which would be formed by winding string through and through a curtain-ring until it was full. It is probable that the momentum of these rings corresponds very nearly with that of the drops before impact, so that when rain is falling on to water there is as much motion immediately beneath the surface as above it, only the drops, so to speak, are much larger, and their motion is slower. Besides the splash, therefore, and surface-effect which the drops produce, they cause the water at the surface rapidly to change places with that at some distance below. Such a transposition of water from one place to another must tend to destroy wave-motion. This may be seen as follows: Imagine a layer of water adjacent to the surface, and a few inches thick, to be flowing in any direction over the lower water, which is to be supposed at rest. The effect of a drop would be to knock some of the moving water into that which is at rest, and a corresponding quantity of water would have to rise up into the moving layer, so that the upper layer would lose its motion by communicating it to the water below. Now, when the surface of water is disturbed by waves, besides the vertical motion the particles move backward and forward in an horizontal direction, and this motion diminishes as we proceed downward from the surface. Therefore, in this case, the effect of rain-drops will be the same as in the case considered above, namely, to convey the motion which belongs to the water at the surface down into the lower water, where it has no effect so far as the waves are concerned, and hence the rain would diminish the motion at the surface, which is essential to the continuance of the waves, and thus destroy the waves.—Nature.

 

SCIENCE FROM THE PULPIT.
By JOHN TROWBRIDGE,

ASSISTANT PROFESSOR OF PHYSICS IS HARVARD UNIVERSITY.

ARE ministers fitted to discuss the bearing of modern science upon religion? This question forces itself upon one who is both a member of a church and a lover of science, and deserves to be carefully weighed by those who have the interests of Christianity at heart. An article by the editor of the Nation, in the issue of December 24, 1874, takes the very sensible ground that a man of science should have no greater authority in controverted religious questions than the most humble member of a church. His views are not entitled to great consideration simply because he is a student of science. This seems to touch the vital part of the question. The history of the world shows, however, that the assumption of exclusive right to treat religious questions with authority, and the barring out of critical in-