ON THE MAGNETIC QUALITIES OF IRON. 
1019 
B. 
Actual value of JHH. 
Value calculated frotu 
the above formula. 
150 
7 
10-3 
300 
31 
31 
500 
80 
71 
1,000 
256 
215 
2,000 
750 
650 
4,000 
2,030 
1,970 
6,000 
3,700 
3,780 
8,000 
5,820 
5,980 
10,000 
8,340 
8,540 
12,000 
11,550 
11,430 
14,000 
15,200 
14,630 
The divergence is becoming considerable at the top of the range, but elsewhere the 
agreement is fair. It should, however, be observed that if we wish to make the curve 
given by the empirical formula coincide with the real curve throughout any short part 
of its range, other, and often very different values must be given to e and 7 ^. Thus, 
if the part from B = 2000 to B = 8000 only is considered—a part wiiich includes those 
values of B which are usual in transformer cores—the formula 
|Hc^I = 0-01 B1-4'75 
will express the results very much more closely. For example:— 
B. 
Actual value of jHril. 
Value calculated from 
the expression O'Ol B^ 
2,000 
750 
740 
3,000 
1,350 
1,345 
4,000 
2 , 0:30 
2,060 
5,000 
2,820 
2,860 
6,000 
3,700 
3,740 
7,000 
4,650 
4,690 
8,000 
5,800 
5,720 
Throughout this not inconsiderable range of magnetization (the region, namely, of 
high permeability) the agreement is good, but other empirical constants are required 
to fit the earlier, and again the later parts of the curve. 
In further illustration of the point, we add a curve (fig. 22), showing the actual values 
of jH c?I in relation to B for the low cycles in the tests of Bing IV., and on the same 
diagram a dotted line is drawn, to show the value found for Mr. Steinmetz’ formula, 
namely, the constant 7 ^ being taken as 0’0034, since that value best accords with 
the tests of Bing IV. throuD-hout the whole raime of mao^netization. It will be 
evident from the diagram that this early portion of the curve is not even approxi- 
G o 2 
