Perkins, Henry, 1803-1889, publisher, Haswell, Barrington, and Haswell, printer, McManus-Young Collection (Library of Congress) DLC · Philadelphia : H. Perkins, 134 Chestnut Street · leaf 52
im of the eye-glass, A. Thespring tube may then be drawn out or shut up tovery minute distances. Thus, the ordinary sliding tubes are super-seded ; nor is any external covering necessary, as the hand in grasp-ing the instrument serves the purpose. If, however, a covering bepreferred, a piece of… … MULTIPLYING THEATRES. Place two pieces of looking-glass, one at each end, parallel toone another, and looking over, or by the edge of one of them, theimages of any objects placed on the bottom of the box, will appearcontinued to a considerable distance. Or, line each of the four sides of the box…
Scientific recreations
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