Page:Popular Science Monthly Volume 20.djvu/557

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541
VIBRATION OF ROCKS IN PATAPSCO VALLEY.

But we have not yet reached the end of our excursion; indeed, we have only entered the threshold of the scientist's sanctum, and the wonders of the arcanum eclipse those of the portico. That mysterious agency or force called electricity has been utilized, not merely for the benefit of bulls and bears, or for hundreds of utilitarian purposes with which we are familiarized every day, but it has been used as a fairy-finger to probe Nature's hidden structure, and, as it were, enable us to feel what the spectroscope has revealed to sight.

Then, again, appliances for obtaining little samples of "stellar space" in the interior of glass bulbs—bottled vacuity—which we may examine at our pleasure, are in themselves curious. Think of a bulb about the size of a cricket-ball containing only one ten-millionth part of one atmosphere, and that part being subdivided into millions and millions and millions of individual portions, and these particles being captured and made to do visible, tangible work; think of a miniature engine with a propeller-wheel being made to revolve and a little rail-way run by projecting these minute particles against the driving-wheel; think of a piece of refractory metal like platinum being so terribly battered by hitting it in rapid succession with a charge of these little molecules that it is made to cry out in fervent heat, to glow with a bright light, and, if this molecular bombardment is continued, even to melt before it like wax; think of the commonest and most uninteresting materials, like burned oyster-shells, being made to shine with a luminosity rivaling the "great carbuncle," or the famous "Kohinoor"; of little pieces of glass outvying the finest emeralds, rubies, and sapphires, when under this marvelous influence—then, we will be ready to admit that, while we work-a-day, matter-of-fact people may not understand the motive that induces the original investigator to plod on in his narrow path, continually prying into some seemingly trivial corner of Nature's vast store-house of knowledge, we can nevertheless appreciate and enjoy the beautiful results which modern Science has to offer as rewards to her votaries, and we can not too greatly venerate the genius of those who could conceive the possibility of such results, and possess the ability to produce them.

 

VIBRATION OF ROCKS IN PATAPSCO VALLEY, MARYLAND.
By FREDERIC GARRETSON, M. D.

THE valley of the Patapsco River, through which the Baltimore and Ohio Railroad passes, presents many interesting subjects to the student of physics and of geology. After passing the junction of the Washington branch at the Relay House, eight miles west of