886 



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



No. til 375- 



61 384. 1 : 5. 



61 385. 1 : 8. 



Manganin Series Resistances: s. d. 



01.375. With \ section for 300 volts 2. 10. 



61.376. 2 sections for 300, 450 volts 3. 16. 



61.377. 2 for 300, 750 volts 6. 0. 



61.378. 3 300, 750, 1500 volts lo. n. n 



01.379. Shunt Plug, */ ohm, for converting the comparing resistance from 1 ohm to 0.1 ohm n. ]:,. i> 



(i 1,380. Resistance Plug, 300 ohms; for putting in circuit as a safety resistance in the measurement of battery 



resistances 0. in. n 



61.381. Battery Box with 72 Dry Cells, in 6 compartments with 4 cells eaih and 4 compartments with 2 cells 



each, with terminals for each compartment 7. 1". u 



61.382. Induction Coil for generating A. C. for measuring electrolytic resistances (Kohlrausch 1 method), for 

 connecting up to from 1 to 2 dry cells 1. l."i. n 



61.383. Telephone for use in measurements with preceding Induction Coil | 0. 8. 



61.384. Projection Moving Coil Galvanometer, Figure, on adjustable stand 4. 0.0 



The galvanometer proper is completely enclosed in a mahogany box and the long horizontal 

 needle plays between two glass plates one of which is provided with a projection scale. 



This very sensitive instrument is intended to be used with the projection lantern and is put in 

 circuit by pressing a button on the top of the apparatus. 



Needle Galvanometers with moving Coil: see below, under the Technical Measuring Instruments. 



61,38."). Model of a Moving Coil Galvanometer with Bifilar Suspension, F i g u r e, after Friedr. 



C. G. Mtiller (M. T., Fig. 185) 1. 16.0 



61.386. Model of a Moving Coil Galvanometer after Kolbe, Figure (Kolbe-Skellon, Introduction 

 to Electricity, Part 11, Fig. Ill), very compact instrument with scale visible at a distance; 



can also be used for zero methods 3. ."i.o 



61.387. - - idem, larger and more sensitive 5. 0. 



61.388. Galvanometer after Deprez-d'Arsonval, Figure, with mirror and needle reading, 

 on ebonite base-plate with glass bell (\V. und K. phys. Prakt., Fig. 27!>; (Ian. -.Man., 



Fig. 762; Gan.-Kcin., Fig. 897), witli polished plane mirror 8. 0. l 



61.389. -- idem, for mirror reading only, without needle 7. in. o 



61.390. Galvanometer after Deprez-d'Arsonval. with mirror reading, on tripod stand, F i g u r e 



(W. u. K. phys. Prakt., Fig. 280), with polished plane mirror 7. 1 .">.( 



The following are given in: 1 steadying resistance, 1 pair vibrating weights for ballistic purpo.-es 

 and 2 damping suspension frames. Sensitivity at I in scale-distance: I nun deflection with approx. 

 1x10 H amp.: resistance of coil, approx. 250 ohms. The time of swing without weights is about 

 d seconds, with weights about 15 second-. 



<>1,3!1. Moving Coil Mirror Galvanometer after K. \\iedemann. Figure, with 3 different 



interchangeable coils; a very neat instrument and highly sensitive 7. .">. 



' 'oil I has a resistance of approx. 100 ohms. Coil II of approx. 20 ohms; Coil III is formed of 

 .'!..") turns of 1 mm thick wire. 



The instrument is covered off on both sides by plate glass which can be raised up for I lie insertion 

 of rubber coils. 



The sensitivity is, when Coil I is used: 1 mm deflection at 1 in scale-distance approx. 



3xlO- amp.: with Coil II approx. lxlO- s amp The duration of the full period of swing is about 

 15 20 seconds. 



ri. 395. 4507. 



