Perkins, Henry, 1803-1889, publisher, Haswell, Barrington, and Haswell, printer, McManus-Young Collection (Library of Congress) DLC · Philadelphia : H. Perkins, 134 Chestnut Street · leaf 46
h to look: here, e, is the eyeof the spectator, p, is theprism, h, the hole in theshutter or pasteboard, s, thespectrum. By a little prac-tice, you will soon becomeaccustomed to look in theright direction, and willsee the colours very bright and distinct. By means of this simple contrivance, white… … 26 SIGHT AND SOUND. into which put a half-sovereign, and fill the glass three-fourthswith water; place on it a piece of paper, and then a plate, andturn the glass upside down quickly, that the water may not es-cape : by looking sideways at the glass, you will perceive a sove-reign at the bottom,…
Scientific recreations
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