900 



Voltaic Electricity. Section 3: Electro-Magnetic Current Measurements. 



N.I. 61 ;,n.-i 



61 505. 1 : 6. 



50796, 61505, 61507, 61509, 61510, 61511. 1 : 6. 



01,5(1."). Demonstration Double Oscillograph with two measuring loops, after AVehnelt, 

 Figures (E. T. Z., 1903, p. 703 and 1904, p. 416), on stand 



Between the poles of an electromagnet excited by D. C., a loop of hard drawn silver wire carries a 

 glass mirror. If this moving system is traversed by fluctuating, pulsating or oscillating currents, and pro- 

 vided that the apparatus is arranged as in above illustration, luminous curves, corresponding to the current 

 curves, are projected on to a screen placed opposite the projection lantern. If now the moving systems of 

 the double oscillograph are connected in parallel on an A. C. network, the current curves can be made 

 to coincide exactly. If now by means of the switch apparatus No. 61,510 a non-inductive re- 

 sistance, then an inductive resistance, and finally a capacity or the two latter simultaneously -- are 

 put in series with the moving system of one of the oscillographs, the resultant current reductions and 

 phase lead and lag, or in other words, the phase displacement between current and voltage, can be shown 

 in a very pretty manner. We send complete description on demand. For Rotating Mirrors see 

 N'os. 61,490 61,494. 



Ol,:>lo. NEW! Switch Apparatus (German Design) for producing Phase Displacements with 

 leading and lagging current, Figure. Price without lantern or other accessories 

 illustrated 



The apparatus consists of a marble slab on mahogany frame, two non-inductive resistances, one 

 sliding resistance, one coil with large, adjustable self induction, one change-over switch, and the necessary 

 terminals for 'connecting a capacity, the oscillograph and the A. C. source. 



s. 



61,507. Diaphragm with two holes, fitting projection lanterns 



(1. 

 0. (I 



61,511. Condenser insulated with paraffined paper, about 12 mfd., for voltages to 120 



61,512. Photograph on glass of the scheme of connections of the double oscillograph in con- 

 junction with Switch Apparatus No. 61,510 0. 





6. 12. 



0. 10. 



61.508. Screen with clamp, for screening the secondary radiation i 0. 0. o 



61.509. Large Lens on Stand 0. 16. 





2. 14. 



1. c> 



01. 500. Oscillograph after Wehnelt, with a metal loop . 3. 0. o 



specially adapted for investigating and demonstrating the curve of the ;irc of A. C. arc lamps and 

 the influence of the choking coil on the same, for checking the working of interrupters etc. 



ill. .">!:'>. Oscillograph after \Vittmann, with a metal loop, Figure 11. o. o 



The oscillograph IKUS converging pole pieces the distance apart of which can be varied. A small 

 ebonite frame is placed in the air gap, which is about 4 mm wide, a current loop of tinsel being stretched 

 across this frame. The loop is conducted over a small ivory pulley and can be evenly adjusted by micro- 

 metrical arrangement. For damping the oscillations of the loop itself, use is made of a very light aluminium 

 frame which is insulated and cemented on to the loop. The electromagnet is arranged to rotate about a 

 vertical a*is so as to render it possible to place the loop vertically. 



The apparatus is used in the same manner as the Wehnelt Hscillographs. the present instrument 

 however being much more sensitive 



Cl. 2740 ', 4957. 



