551 



Prof. T. li. Lyle : l^rcluninar/j Account of 

 Iron Wire Ring. No. II. 



r in C circuit = 30,000 w. r in F circuit 60,000 w. 

 C by centiampere balance at start *491 amp. 

 „ „ „ at finish "490 amp. 



Speed at start J 000 -^ in 306 sec. . 5-46 



at finisb 1000 -^ in 30-8 sec. 



X = 



10-^ 



amp. 





Gralvanometer Readings. 





Galvanometer Readings. • 



Divided 



Zero= 



= 100. 



Divided 



Zero = 



= 100. 1 



Circle 

 Readings 







Circle 

 Readings 





1 











(Degrees). 



Current. 



Flux. 



(Degrees). 



Current. 



Flux. i 







115-8 



1380 



90 



84-4 



62-0 



5 



110-2 



136-8 



95 



89-9 



63-2 



10 



104-7 



1351 



100 



95-5 



64-8 



15 



99-0 



1330 



105 



101-1 



66-9 



20 



93-3 



11:9-8 



110 



1068 



70-0 



25 



88-0 



124-7 



115 



112-1 



75-2 



30 



83-3 



114-6 



120 



116-8 



85-3 



35 



79 8 



980 



125 



120-2 



102-0 



40 



76-2 



80-7 



130 



123-8 



119-3 



45 



72-4 



67-9 



' 135 



127-6 



13-21 



50 



68-6 



621 



140 



131-4 



1380 1 



55 



65-9 



59-6 



1-15 



134-0 



1^0 5 i 



60 



64-8 



58-7 



150 



135-1 



141-5 I 



65 



65-2 



58-7 



155 



134-7 



141-4 1 



70 



67-3 



59-1 



160 



132 6 



141-1 ! 



75 



70-3 



59-5 



165 



129-4 



140-8 I 



80 



74-4 



601 



170 



125-4 



140-1 ! 



85 



79-1 



60-9 



175 



120-6 



1393 1 



90 



844 



62-0 



j 180 



i 



115-2 



138-2 



In taking- the above readings the galvanometer-key was 

 kept down all the time. This is not the best method, as most 

 galvanometer suspensions will show elastic fatigue. When 

 greater accuracy is desired, deflexions on either side of 

 the zero can be taken for each position of the movable 

 brushes. It is not necessary, as was done in the above 

 set, to take readings over the whole wave ; readings over half 

 a wave are sufficient [see § 12] . Telescope and mm. scale, 

 placed about 40 cms. from the galvanometer^ were used ; 

 estimation to 0*1 mm. 



8. From any 18 consecutive current-deflexions got from 

 the above table, their square root of mean square will be 

 found to be 23 76, and the galvanometer-factor being 

 5*46 X 10~^, the current in virtual amperes is by § 3 

 5-46 rT 



10' 4M 



23-76 



0-46 

 10« 



30000 



30-7 

 1000 



4x0-00061 



23'76 = '4897 amp., 



