The outlines of physics: an elementary text-book . ed in this experiment dependupon persistence of vision. The observer obtains a suc-cession of views of the tuning fork; each so short thatthe fork does not move appreciably before the light iscut off. Each successive, instantaneous view shows thefork in a position slightly different from the precedingone. This succession of views overlaps upon the retinaand is blended by the mechanism of vision into a con-tinuous impression. The impressio;i produced is that ofa fork vibrating with a very slow motion. Note that the amplitudeof vibration of the
The outlines of physics: an elementary text-book . ed in this experiment dependupon persistence of vision. The observer obtains a suc-cession of views of the tuning fork; each so short thatthe fork does not move appreciably before the light iscut off. Each successive, instantaneous view shows thefork in a position slightly different from the precedingone. This succession of views overlaps upon the retinaand is blended by the mechanism of vision into a con-tinuous impression. The impressio;i produced is that ofa fork vibrating with a very slow motion. Note that the amplitudeof vibration of the tuning fork is very considerable; the prongs beingone instant spread wide apart and at the other end of their excursionbeing bent strongly together as in Fig. 319. l/ Fig. 319. 350 THE OUTLINES OF PHYSICS 316. ExPEEiMENT 100. —Tuning Fork Tracings. Apparatus: (1) A wooden track about 1 m. long, consisting of two parallelguides between which a block slides smoothly. (2) A wooden support (S, Fig. 320) consisting of an upright piece, STvpre po„K. Fig. 320, 20 cm. square and 2 cm. in thickness. This is screwed to a base con-sisting of two blocks hinged together as shown in the figure. (3) Two large tuning forks and a bow. (4) Several pieces of glass (cut from window glass) about 5 and 20 cm. long. Procedure : (a) To one end of a laboratory table clamp the support S. About12 cm. above the table bore a hole through the upright to fit the shankof the tuning forks. Clamp one of the forks to the support by slippingthe shank through the hole and bolting it into place with the nutused to fasten the fork to its sounding box. (6) From a bit of thin sheet metal, ferrotype iron, or copper foil,cut a slender, pointed strip about 4 cm. long. Bendthis strip at right angles as in Fig. 321, and fastenit with wax to one prong of the fork. (c) Smoke one of the pieces of glass over a candleflame, and fasten it, smoked side uppermost, to thesliding block by means of thumb tacks. Place theb
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishe, booksubjectphysics
