Upon the electrical experiments to determine the location of the bullet in the body of the late President Garfield; and upon a successful form of induction balance for the painless detection of metallic masses in the human body . a Wheatstone Bridge, excepting by very delicateand accurate observations. To test whetlier a short-circuitedconvolution would produce eifects analagous to those observed,a piece of copper wire was bent into an annular form and theends coimected togethei-. On bringing this metallic ring neara pair of coils, (A, B, Fig. 19,) properly adjusted to silence, thel)alance was
Upon the electrical experiments to determine the location of the bullet in the body of the late President Garfield; and upon a successful form of induction balance for the painless detection of metallic masses in the human body . a Wheatstone Bridge, excepting by very delicateand accurate observations. To test whetlier a short-circuitedconvolution would produce eifects analagous to those observed,a piece of copper wire was bent into an annular form and theends coimected togethei-. On bringing this metallic ring neara pair of coils, (A, B, Fig. 19,) properly adjusted to silence, thel)alance was loudly disturl)ed. The copper ring (C) was heldas shown in Fig. 19, and the balance could not then l»e re-stored by any adjustment of the coils. A position of mininnnnsound was all that could be obtained, and the liearing distancewas enormously reduced. This was j^itmC facie eviden(;e of thenature of the defect. The (ioils (Fig. 18) were then removed from their case, buta cursory examination revealed no defect. Upon trial, how-ever, (being arranged, as formerh, in Fig. 17,) a Ijalance couldnot be obtained, and the hearing distance was only al)out -1 29 cm. The defect was thus detinitoly located in the coils Upon close examination it was noticed tliat tlie outside con-volutions of the piimary (toil were slightly frayed at one part,hut it appeared hardly possihlc that so great a defect could hedue to so apparently slight a cause. ITowevei, to test the mat-ter, 1 removed the outside layer of wii-cs and then tested thecoils again. Result : The defect had \anislied—a perfect halance was oh-tained, and the hearing distance was again 13 The coils were then replaced in their case and the completedinstrument tested. The lower wooden Idock B (Fig. 18) was These experimeuts have revealed the cause of the extriuie difficulty alwaysexi)erienced iu obtainiug a i^erfect lialauce with coils of fine wire. I haverecently used an Induction Balance to test the condition of t
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Keywords: ., bookauthoryapamphl, bookcentury1800, bookdecade1880, bookyear1882
