Theory and practice of the electric telegraph; a manual for operators and students (1875)
Churchill, Charles Henry, d. 1904. [from old catalog] · Oberlin, Ohio, Sherman & bros. · leaf 56
directionit is a left-handed helix. 3. Relation of Poles to the Current.—1. What determines the direction ofthe poles of the electro-magnet? The direction of the pole depends upon the direction of thecurrent. In the figure the current enters the helix near S. 2. What is the rule? The south pole… … This wordmeans a tubu-lar magnet. Itis technicallyapplied to a he-lix whose ends* are bent backthrough thecoil to the mid-dle,where theyemerge with-The Solenoid. out contact in any part. Two such are seen in the annexed figure. 2. Why is it called a magnet? Such a helix is found to possess all the…
Telegraph
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