Perkins, Henry, 1803-1889, publisher, Haswell, Barrington, and Haswell, printer, McManus-Young Collection (Library of Congress) DLC · Philadelphia : H. Perkins, 134 Chestnut Street · leaf 53
heback and front of which are inserted two thin boards, the frontone, B, reaching about half the height ofthe frame, and the back one being mova-ble, by sliding in grooves, for betterfixing the paper to be written on, C, toa roller at top, with a handle and ratchetworking into a spring. To use the… … SIGHT AND SOUND. 33 B, and turning, with the left hand, the ratchet, the distance ofthe lines may be regulated by the number of clicks caused bythe spring on the ratchet. D, is a foot to support the apparatus,which, however, should be light enough to be held in the handas a slate. PORTABLE…
Scientific recreations
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