. The medical and surgical uses of electricity. . the left. In this way all the sectorswill become more and more highly charged, the front sectors carrying overnegative charges from left to right, and the back sectors carrying over GOLD-LEAF ELECTROSCOPE. 15 positive charges from right to left. At the lower half of the diagram asimilar but inverse set of operations will be taking place. These and theother forms of influence machines are called rotation multipliers, becauseby their rotary motion they multiply by successive transmissions the chargeof electricity that they communicate. Electric S
. The medical and surgical uses of electricity. . the left. In this way all the sectorswill become more and more highly charged, the front sectors carrying overnegative charges from left to right, and the back sectors carrying over GOLD-LEAF ELECTROSCOPE. 15 positive charges from right to left. At the lower half of the diagram asimilar but inverse set of operations will be taking place. These and theother forms of influence machines are called rotation multipliers, becauseby their rotary motion they multiply by successive transmissions the chargeof electricity that they communicate. Electric Spark.—An interesting phenomenon connected with the elec-tric machine is the electric spark which is drawn from the conductorwhen the finger is presented to it. The positive electricity of the conductor decomposes the electricity ofthe body, attracting the negative and repelling the positive, and, whenthe tension is great enough, these opposite electricities overcome the re-sistance of the air and recombine with a spark and crackling sound. The. Fig. spark is accompanied by a prickly sensation. When the spark is short itis straight; beyond two or three inches in length it becomes curved orzigzag, like the lightning in the sky. The human body may be charged with electricity by sitting on an in-sulated platform and touching the conductor of an electric machine. When the body is thus charged, the hair diverges, a peculiar sensationis felt in the face, and if any other person standing on the ground touchesone so charged he receives a spark, with a crackling sound and a prick-ling sensation. Gold-Leaf Electroscope.—^^ \hS.^ instrument we are enabled not onlyto detect the presence, but to determine the kind, of electricity that mayexist in any body. i6 ELECTRO-PHYSICS. Fig. 12 represents Bennetts electroscope. ^ is a tubulated glassshade, enclosed at its lower end by a metallic cover, by means of whichit communicates with the ground. A metal rod, fitting in the tubule ofthe shade,
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyo, bookyear1896
