Natural Philosophy for Common and High Schools (Paperback)

This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1872 Excerpt: ...the organ the musical sounds are caused by vibrations of columns of air. A large bellows is kept full of air; the organist, by pressing the keys of the organ, opens the way from this bellows into one or more of the many pipes of the instrument, and jets of air going into the pipes at the bottom, make the air throughout their whole lengths vibrate, and these vibrations produce the musical sounds. Upon what does the pitch of organ-tones depend?--The pitch of the tone in an organ depends on the length of the organ-pipe. The shorter the pipe the higher the pitch will be. The lowest note used in music is made by an organpipe, open at the top, whose length is 32 feet. If the pipe is closed at the top, a note of the same pitch will be made by a pipe 16 feet in length. The highest notes are made by pipes which are only a few inches long. LIGHT. What are luminous bodies?--Luminous bodies are those which produce light. The sun is a luminous body because it shines by light which itself produces. The flame of a candle, and a red-hot iron ball, are also luminous bodies for the same reason. What are non-luminous bodies?--Non-luminous bodies are those that do not produce light. If they shine at all it is because they first receive light from some other source and then throw it off again. A piece of rock or of wood, a flower, a cloud, --all these are non-luminous bodies. The moon is also non-luminous, for while it shines with a steady and bright light, vet it produces none itself. What we call the moonlight is light which goes from the sun to the moon first, and is then thrown from the moon to us. What are transparent and opaque bodies?--Some bodies, like glass and air, allow light to pass freely through them; all such are called transparent bodies. Others, like iron and wo..