1030 
PROFESSOR J. A. EWIKG AND MISS H. G. KLAASSEN 
constant, the current in Q was applied. This gave the line cd ; then the current in 
Q was reversed, giving the dotted line de, and re-reversed. Finally, after several 
reversals of the current in Q, the process of reversal gave the closed figure shown by 
the full line fgf. Next (the current in Q having been stopped), the steady current in 
P was increased to a value which brought the magnetism up to h. Then the applica¬ 
tion and reversal of Q’s current gave the lines, hi, ij, jlc, the cycle finally settling down 
after several reversals into the form shown by the full lines, Jdk. The same description 
applies to each of the loops which are seen higher in the diagram. The highest ones 
lie in what is often called the region of saturation. Throughout all these successive 
Fig. 31. 
operations the current in Q, whose reversal formed the loops, had the same extreme 
value. The experiment shows how, as might be expected, the reversals of a given 
magnetizing current produce less and less magnetic change as the total magnetism is 
increased. It also illustrates one of the minor consequences of magnetic h 3 "steresis, 
namely, that a periodic force, applied in addition to a constant force, does not imme¬ 
diately produce cyclic effects; it is only after several repetitions of the reversal that 
the curves become closed. During the interval of “ accommodation ” (to use the term 
which has been applied in other instances where the same feature occurs in the 
phenomena of magnetization) the mean value of the magnetism is rising, as a conse¬ 
quence, one may say, of the molecular shaking which is involved in the process 
of reversal. 
A more striking example of the influence of the molecular shaking which is brought 
