104 A. S. Kimball—Magnetic Strains in Iron. 
current, and accuracy in weighing was not at first deemed 
essential. The experiments described, and many others of a 
similar — seem to establish the following conclusions. If 
on bar surrounded by a helix and loaded as above be 
sabienes several times to the action of a constant magnetizing 
current: 1st. The first time the current is made, the deflection 
) 
the weight produces a oe deflection in the bar than before 
the current was passe 3d. The second and subsequent cur- 
succeeding current is always the same. The same is true of 
the deflection after each current, but the deflection previous to 
the passage of the first current lies between those just specified. 
5th. Although the second and subsequent currents have no 
power for the production of additional permanent magnetic 
strain as long as the load remains constant, yet, if the load 
upon the bar be increased, the first current after such a change 
produces a less effect than those which follow. 6th. If a part 
of the load be removed from the bar, the first current produces 
a greater change in deflection than those which follow; in this 
case, the deflection of the bar is permanently diminished by 
the first current. This may be illustrated by an extract from 
a series of experiments made with a diminishing load upon the 
bar—8 lbs. have just been removed. 
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e changes in the load upon the bar, heretofore referred to, 
have "bonn made while the current was broken. 7th. If the 
load be increased while the current is on, the deflections when 
the current is broken will be constant, and the deflections with 
the second and subsequent currents will be greater than those 
obtained by increasing the load. The changes in deflection 
the first time the current is broken will be greater than those 
which follow. 
Iilustration—8 lbs. have just been added to the load while 
the current was passing. 
AC eee: Wee eet Pee ee 2 
63 36} este Se aes Ss Oe 
a 1 — cc we 
65 = 363 ee ee 28 
8th. If the ad = PORES while the current is on, the 
deans when the current is broken will be constant and 
the deflections with the second and subsequent currents will 
