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.
LIGHT AND LENSES "LIGHT is the agent or force by the action of which, upon the organs of sight, objects are rendered visible" and, as such, it is imponderable; it has no physical body which would permit our senses to ascertain its nature, but it has certain effects on them, especially on the organs of sight. Also it is the source of cer tain physical phenomena which permit the expression of hy pothesis and theories which lead to an understanding of its nature. Several are the known sources of light; heat, electricity, chemical combinations, phosphorescence. As light is the direct consequence of one of these causes, it is quite evident that through the cause a certain disturbance is created, a stimulus which is, translated into the capacity of performing a certain work, i.e., into energy, which energy we call light. Heat is one of the principal and most common causes of light. It has been ascertained that a non-luminous body, placed in the dark, begins to become visible when its temperature is raised 500 to 600 degrees and that its luminosity increases with the increase of the temperature. Such body, then, does not create light of itself, but by sub mitting it to the action of heat, it provokes a very special dis turbance which becomes manifest as light only when heat has reacted upon the body in a certain quantitative measure, and is subject to variations, according to the entity of this quantity. The light emitted by the sun is the result of the extreme heat of its mass and of the state of incandescence of the vapors and gasses surrounding it. The temperature of the sun has been estimated at somewhat below 6,000 degrees Centigrade, nearly 11,000 Fahrenheit.