Sunday, November 29, 2009

Best of BoK Volume Nine

These first two plates illustrate an article titled "The Color of the Stars."

The fine print on THE LIGHT THAT EXPLAINS THE STARS TO US reads as follows:
When pure light, as from a white-hot iron, passes through a glass prism, it is broken up into seven colors, called the spectrum, as shown in the first picture. But light from the sun shows, in addition to the colors, various lines, as seen in the second picture. These lines are caused by some of the different substances that compose the sun. Although here we see only a few lines, the sun's spectrum really shows over 2,000 lines. The third picture is the spectrum of a star, Sirius, and when compared with that of the sun, it shows that the stars are made of the same materials as the sun and earth, because the lines in the spectrum for different substances always appear in the same position in relation to each other, as can be seen by comparing these spectra of the sun and Sirius. Although the spectrum color of the metal sodium is yellow, as in the fourth picture, this appears dark in the sun and star spectra, because of the intense light behind it, just as a gas-jet seen in front of the sun's disc appears black; but of course sodium is in the same position in all the spectra.

This picture shows us how the spectroscope is used to enable men to catch the light of a star, and by passing it through a glass prism to bread up the light into various colors. As different metals give off different colors, we can in this way tell of what the stars are made. Ths picture does not show the spectroscope, but illustrates the principle.

This last illustration, A WHEEL A QUARTER OF A MILE ROUND, reminds me of a postcard that was posted recently for Postcard Friendly Friday. The caption reads:
Some of you have seen this gigantic wheel which used to be at Earl's Court in London. This was not the first great wheel to be built. An American engineer, Mr. G. W. Ferris, had seen those curious little upright roundabouts that come to the country fairs, and he thought out the idea and built for the World's Fair at Chicago a big wheel of iron that carried 1,440 people at one time. Then the Earl's Court wheel was built, and this was much more wonderful that the other. It was 300 feet across, and the towers that supported it were 175 feet high. The axle, weighing 54 tons, was hollow, and people could walk through it from one side to the other while the wheel was going round with its 1,600 passengers. The great wheel was turned by a big engine that needed only one man to work it.

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