Perkins, Henry, 1803-1889, publisher., Haswell, Barrington, and Haswell, printer., McManus-Young Collection (Library of Congress) · Philadelphia : H. Perkins, 134 Chestnut Street, MDCCCXXXVIII [1838] · leaf 55
SIGHT AND SOUND. 33 B, and turning, with the left hand, the ratchet, the distance of the lines may be regulated by the number of clicks caused by the spring on the ratchet. D,is a foot to support the apparatus, which, however, should be light enough to be held in the hand as a slate. PCRTABLE… … part, with a screwed cavity in it, to receive a short screwed tube, with a small hole in its centre, made to fit the steel stem of the spring forceps ; a corresponding hole being madeat the bottom of _ the screwed cavity, where is lodged a piece of perforated cork; which, being pressed upon by the…
Juvenile literature · Scientific recreations
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