388 



SUBMABINE CABLE LAYING AND BEPAIRINGP, 



Similarly, scale 3 of 400 ohms is in parallel with two coils 

 on scale 2, value 400 ohms^ in all positions of the slider. 

 Therefore, the resistance between the slider contacts on scale 2 

 is 200 ohms — namely, that of one coil only, although it em- 

 braces two. The actual resistance of scale 2 is, therefore, 

 10x200 = 2,000 ohms. In the same way, scale 2 of 2,00a 

 ohms is in parallel with two coils on scale 1, value 2,000 ohms, 

 in all positions of the slider. Therefore, the effective resistance 

 between the slider contacts on scale 1 is 1,000 ohms — namely, 

 that of one coil only, although it embraces two. The actual 



Fig. 231. -Sullivan's Pattern of Universal Shunt. 



resistance of scale 1 is, therefore, 10x1,000 = 10,000 ohms. 

 Hence we have a total resistance of 10,000 ohms, divisible into 

 10x10x10x10 parts on the four scales respectively — that 

 is, into 10,000 equal parts. 



In the illustration the slide reading is 4,272. This means 

 4,272 parts out of 10,000. The resistance of the shunt, as 

 before stated, does not come into the calculation. All we have 

 to deal with is that the total resistance across the galvanometer 

 is divisible into 10,000 equal parts, of which 4,272 parts are 

 read off the sliders. The multiplying power of the shunt for 



10,000^2-34. That is, multiplying the deflec- 



this reading is 



4,272 



