. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. Fig, 59, plate a and turns by friction on that plate. It is bestto have a thin india rubber ring upon the friction pulleyto insure it from slipping. Above the pulley the mirrorm is so mounted as to swing in azimuth, and is madeto do this by a wire fastened to itat its hinge, and bent into a loop /at its lower end, which is oppositethe face of the pulley s. Anothertwist in the wire at o will be needed,for a pin which is fast in the post/; this will make a le
. The art of projecting. A manual of experimentation in physics, chemistry, and natural history, with the porte lumière and magic lantern. Fig, 59, plate a and turns by friction on that plate. It is bestto have a thin india rubber ring upon the friction pulleyto insure it from slipping. Above the pulley the mirrorm is so mounted as to swing in azimuth, and is madeto do this by a wire fastened to itat its hinge, and bent into a loop /at its lower end, which is oppositethe face of the pulley s. Anothertwist in the wire at o will be needed,for a pin which is fast in the post/; this will make a lever of thewire /, with the fulcrum at o, and ifit is properly fastened to the hingeFiff. 60. q£ |-jjg mirror will cause it to vibrate in a horizontal plane when the plate a ACOUSTICS. 79 A somewhat similar arrangement is made for theother side, save that the friction pulley / has its bear-ing made fast in a separate piece r, which is so fastenedto the end of a long screw d that the whole fixture canbe moved to or from the centre of the plate a. Thepiece c is furnished with two guides, which keep itsteady in any place where it is put. The mirror m ismade to tilt in a perpendicular plane by an arrange-ment quite similar to the former one, save that the wireconnection has its lower end bent into a horizontalloop, through which a pin in the face of the pulley / isthrust This is practically an eccentric, and, beingdirectly fastened to the hinge of the mirror m\ gives toit an angular motion proportional to the distance of thepulley face-pin from the centre. The mirrors shouldbe not less than two inches square. If then the pin isan eight of an inch from the centre of the friction pul-leys, they will have ample angular motion; much largerthan can ever be got fro
Size: 1361px × 1837px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1870, bookpublisherbosto, bookyear1877
