We use Optical Character Recognition (OCR) during our scanning and processing workflow to make the content of each page searchable. You can view the automatically generated text below as well as copy and paste individual pieces of text to quote in your own work.
Text recognition is never 100% accurate. Many parts of the scanned page may not be reflected in the OCR text output, including: images, page layout, certain fonts or handwriting.
18 Visual Education
Italian, Galileo, had independently invented the telescope. Then, for the first time in the history of the human race, men saw the sun, moon, and planets with optical aid. Although the telescope of Galileo was small and, when judged by modern stands, very poor, yet every observation through it was an adventure comparable to a voyage across an unknown sea, and the discoveries made with it were as marvelous as the new lands which Columbus and his followers found by sailing westward from Europe.
In 1610 Galileo finished his third telescope, which magnified thirty-three
The Yerkes Observatory (from the southwest) of the University of Chicago, located near Williams Bay, Wisconsin, on the shores of Lake Geneva. The large dome contains the great 40-inch Yerkes refractor. The smaller dome at the right contains a two-foot reflector, and the other small dome a 12-inch refractor.
diameters. With it he discovered four of the satellites of Jupiter, the rings of Saturn, mountains and plains on the moon, spots on the sun, and the rotation of the sun. For half a century telescopes were used exclusively for observing the surface characteristics of celestial bodies. Then it was realized that they could be made instruments for precise measurements, and this use has become more important than the former.
Optically a telescope consists of two parts: (a) an objective lens, or a concave mirror, which brings the light to a focus and forms an image of the object ; and (b) an eye-piece, which magnifies the image and enables the observer to see it. In case an objective is employed to focus the rays, the light passes through a lens and the telescope is called a refractor. When a concave mirror is used to bring the rays to a focus the telescope is called a reflector. Eefractors are generally used for visual work and reflectors for photographic.