ELECTRODYNAMIC QUALITIES OF METALS. 
63 
removed ten times in rapid succession, and the wire finally left with only the per¬ 
manent weight of 1 lb. hanging on it. Then beginning with +M, a magnetizing 
current of small amount was applied, and the effect measured by the “throw ” of the 
ballistic galvanometer. The weight of 14 lbs. was then applied and removed ten times 
in succession, the circuit broken with nothing but the permanent weight of 1 lb. 
hanging on the wire, and the deflection of the ballistic galvanometer again noted. 
The same cycle of operations was then repeated for higher and higher strengths of 
current until ten cells were placed in circuit with the magnetizing coil. 
The same process was then followed with the — M. 
These experiments were repeated also at both temperatures with 21 lbs. as the 
weight applied and removed ten times before each operation. Curves (1), of Diagrams 
VI., exhibit the results for 14 lbs., and curves (2) those for 21 lbs. 
A very striking feature of these results is the great excess of the deflection pro¬ 
duced by —M over the deflection produced by -f-M. It cannot but be due to the 
terrestrially-induced magnetism existing in the wire each time before the current is 
made in either direction. 
Comparing the results for the ordinary temperature with those for 100° C., 
we see that the effect at the higher temperature is always considerably less than at 
the lower temperature. Thus, taking the 21 lb. curves YI. (2), the deflection after 
— M with the greatest magnetizing force is 320 for the lower temperature, and about 
250, or 22 per cent, less, for the higher, and for the same magnetizing force the other 
deflections are less at the higher temperature than at the lower, in nearly the same 
proportion. 
213. Immediately after the results for the temperature 1 00° C., shown in curves (2), 
had been obtained, an experiment was made to determine the amount by which (as 
stated in the Preliminary Notice of June 10, 1875, § 7) the effects of making and 
breaking the circuit of the magnetizing coil and battery when the wire is pulled 
exceed the effects of the same operations when the wire is free from pull. The process 
was the same as that described in § 212, except that after each ten “ ons ” and “ offs ” 
the weight of 21 lbs. was put on and left in the scale-pan and the circuit made or 
broken before it was again removed. The experiment was made at only one tem¬ 
perature, 100° C. The results are given in the curves YI. (3). 
A full examination of the results shown in these Diagrams YI. (1), (2), (3), must 
be reserved for a later communication ; and further experiments will be necessary to 
elucidate them. Meantime it is interesting to see by comparing the curves of VI. (3) 
with the curves of YI. (2) for the same temperature (100°), that the effect of the 
— M is greater with the pulled than with the unpulled wire for every degree of 
magnetizing force ; while the effect of the +M is greater in the pulled wire for 
magnetizing forces less than 250, and greater in the unpulled wire for magnetizing 
forces exceeding 250. This was to be expected from the previously proved (§§ 209, 
210) greater magnetic susceptibility in the pulled than in the unpulled wire, when the 
