736 
PROFESSOR F. G. BAILY OR THE HYSTERESIS OF 
Table VIII.—Soft Iron Armature of 250 Plates of thickness '0081 centim. Speed, 
35 revs, per second. Diagram 8. Starting with maximum current and 
decreasing. 
B. 
.. „ 
Hyst. in ergs 
per cub. centim. 
per rev. 
B. 
Hyst. in ergs 
per cub. centim. 
per rev. 
B. 
Hyst. in ergs 
per cub. centim. 
per rev. 
18,800 
13,500 
17,100 
16,000 
9.300 
9,250 
18,700 
13,800 
16,900 
16,100 
8,300 
7,800 
18,600 
14,000 
16,500 
15,900 
7,550 
7,050 
18,500 
14,900 
16,100 
15,900 
6,070 
5,120 
18,300 
15,400 
15,800 
15,400 
5,150 
4,000 
18,000 
15,600 
15,100 
15,000 
3,960 
2,680 
17,800 
15,750 
14,000 
14,600 
17,600 
15,800 
11,600 
11,900 
17,500 
15,900 
10,500 
10,450 
Eddy currents 
= 6-0 x 10-7 B2. 
Table IX.—Hysteresis and Induction in Soft Iron Armature of 250 Plates of 
thickness '0081 centim. The Armature slowly turned and then left at rest and 
the reading taken. Diagram 9. 
B. 
Hyst. in ergs 
per cub. centim. 
per rev. 
B. 
Hyst. in ergs 
per cub. centim. 
per rev. 
B. 
Hyst. in ergs 
per cub. centim. 
per rev. 
8,300 
6,370 
13,300 
11,200 
16,600 
13,300 
9,800 
7,900 
13,900 
11,700 
17,400 
12,700 
10,500 
9,100 
14,400 
12,500 
18,200 
11,900 
11,500 
9,800 
15,100 
11,900 
18,300 
10,800 
12,400 
10,600 
16,100 
12,800 
18,500 
10,600 
In Diagram 6 is given the first part of the curve plotted on a magnified scale, 
and determined by means of a very weak spring, so that the deflexions were large. 
The initial values are small, but the increase is rapid up to an induction of 1,400, 
after which the curve becomes more nearly straight. 
The effect of violent vibration was tested with this armature by comparing the 
readings taken with the armature almost tight in its bearings, and the magnet 
running very smoothly, with the readings taken when the armature was very loose. 
This has the effect of causing excessive vibration, the armature rattling to and fro at 
every revolution. As might be expected, the hysteresis is diminished (Diagram 7), 
but not by much, and it may therefore be concluded that the small vibration present, 
under normal working, does not influence the values to any appreciable extent. 
A similar experience of the comparatively small effect produced by violent 
mechanical vibration is mentioned by Evershed and Vignolles (‘Electrician/ 15th 
and 22nd May, 1891). 
