Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . a sprmg near B. When the rod islifted by the currentin the coil, C, itsupper end raises thehandle of the ham-mer, A guiding wire,R, keeps the rod ver-tical. The circuit isbroken at B, by thelifting of the handle,and is renewed whenthe rod Axial Revolving Bar.—In the instrumentrepresented in Fig. 115, an iron bar is suspendedwithout visible support by the action of a currentflowing in the helix which surrounds its upper half,the bearings abo
Davis's manual of magnetism : including galvanism, magnetism, electro-magnetism, electro-dynamics, magneto-electricity, and thermo-electricity . a sprmg near B. When the rod islifted by the currentin the coil, C, itsupper end raises thehandle of the ham-mer, A guiding wire,R, keeps the rod ver-tical. The circuit isbroken at B, by thelifting of the handle,and is renewed whenthe rod Axial Revolving Bar.—In the instrumentrepresented in Fig. 115, an iron bar is suspendedwithout visible support by the action of a currentflowing in the helix which surrounds its upper half,the bearings above and below serving only as bar is made to rotate by transmitting the bat-tery current through either half. This mode ofsuspending the rotating bar was first suggested byDr. Boynton, The screw-cup A, on the stand, con-nects with the brass pillar, and thence with one endof the coil. The other end of the coil dips into mer-ciuy, contained in a circular cistern of ivory. Thiscistern is supported below the helix by an arm at-tached to the pillar, and has an opening in its centreto allow the bar to pass through. A bent wire, pro-. 176 DAVISS M ANU A I* jecting from the middle of the bar, conveys the cur-rent from the mercury through its upper half to the„. -jg cup B. Some non- conductor of electrici-ty, interposed at I, in-sulates B from the armwhich supports it. IfA and B are connect-ed wilh the battery^and the cistern containsmercury, the currenttraverses in successionthe helix and the up-per half of She bar*Since the bar becomesan electro-magnet bythe influence of the coil, it rotates rapidly on itsaxis,, in the same manner as the magnet described in§ 167. The cup C connects with the lower end ofthe bar, and, by uniting A and C with the battery,the current traverses the lower half, also producingrotation. 282. In Sillimans Journal for March, 1847, will befound a figure and description of a similar instrument,contrived by Dr. Page, in which no mercurial con-nectio
Size: 1492px × 1674px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1800, bookdecade1850, booksubjectmagnetism, bookyear18
