The wonders of modern mechanismA résumé of recent progress in mechanical, physical, and engineering science . machines turned out and verifying by actual test theaccuracy of each individual machine manufactured. Thistester of testing-machines will indicate a variation of fourounces in half a million pounds. A weight of two hun-dred grains laid on the main platform of this remarkablemachine is sufficient to put in motion material weighingmore than twenty thousand pounds, as shown by a varia-tion of the needle the fiftieth part of an inch, and the sen-sitiveness is the same whether loaded or not
The wonders of modern mechanismA résumé of recent progress in mechanical, physical, and engineering science . machines turned out and verifying by actual test theaccuracy of each individual machine manufactured. Thistester of testing-machines will indicate a variation of fourounces in half a million pounds. A weight of two hun-dred grains laid on the main platform of this remarkablemachine is sufficient to put in motion material weighingmore than twenty thousand pounds, as shown by a varia-tion of the needle the fiftieth part of an inch, and the sen-sitiveness is the same whether loaded or not loaded. 32 388 WONDERS OF MODERN MECHANISM. THE SPECTROSCOPE. A Wide-spread Field of Research opened up by an Instrumentthat was at first little understood. To that wonderful instrument, the spectroscope, we owenearly all the recent increase in knowledge of the stars. Ittells us of what they are made, and the direction and speedin which they are journeying. Let us first consider whatthe instrument is, and then the principles on which itoperates. In its simplest form it is a glass prism, through Fig. METHOD OF OBTAINING A SPECTRUM. which a ray of light is allowed to shine. This prismdisperses the light, giving the beautiful rainbow colorsthat children admire. These colors arrange themselvesnaturally in the order of red, orange, yellow, green, blue,and violet, and their graduations, and form what is calleda spectrum. This spectrum is usually viewed through amagnifying eye-piece, like that of a telescope. There isalso usually a minute scale, whose image is thrown uponthe spectrum to enable the observer to measure it. Insteadof the scale a fine wire or line of light from a slit may bemoved over the spectrum, and by means of a micrometer- THE SPECTROSCOPE. 389 screen the movement or distance of any i)oint of the spec-trum from any other can be read off. The tube throughwhich the light enters should be a collimating tube—that is,a tube having glass lenses that cause the ray
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Keywords: ., bookcentury1800, booksubjectmachinery, booksubjectmechanicalengi
