890 



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



\0. fil 



61 407 and 61 409. 



12. 



0*0 0*0* 



<> 1 W ".s 



61 412 A. 



61 411. 1 : r. 



61 412. 1 : 3. 



5. o.o 



61.408. Simple Reading Telescope for preceding, for fixing direct on galvanometer, similar 



to Fig. 61,397, p. 888 J. 10. 



61.409. Objective Reading Device for Wall Galvanometer, Figure, for fixing to roof, 

 illuminated by a glow lamp; scale 0.5 m long, with vertical adjustment: without leads 1. 10. n 



The apparatus on which measurements are to be taken can be set up on a table immediately 

 below the reading device, thus saving a good deal of room. The galvanometer deflections can conve- 

 niently be observed. The galvanometer must have a concave mirror. 



61.410. - - idem, with Nernst Lamp, giving a veiv briirht image, suitable only for 110 to 

 220 volt D. C 



Unless otherwise ordered, Nos. 61,409 and 61,410 are supplied for IK) volts. 



61.411. Moving Coil Mirror Galvanometer for demonstration purposes. Figure, with two 

 different groups of windings on the same moving coil, one of which can lie used for 

 damping; also with arrangement for increasing the period of swing for ballistic purposes; 

 including fixed damping resistance 



The sensitivity is: for the group of turns of approx. 100 ohms: 1 nun deflection at 1 m = approx. 

 4 xlO-'-' amp.; for the second group of 10 ohms, approx. 4 xlll - amp. The duration of the complete 

 period of swing without weights is approx. 6 seconds: with weights, approx. !."> second-. 



For using this galvanometer as a reflecting instrument, the bracket, etc. listed under No. >1,342 

 is suitable. 



n. 49:<fi, 3832, 



9. 0.0 



