MESSRS. G. F. C. SEARLE AND T. G. BEDFORD 
‘)4 
Current 
(amperes). 
Deflexion. 
Diminution, 
per cent. 
0 
141 
0 
•143 
139 
1-42 
•212 
137 
2-84 
•350 
132 
6-39 
•518 
127 
9-93 1 
•664 
122 
13-5 1 
1-123 
109 
22-7 j 
In an experiment made on Mai'ch 7 the wire was subjected to tension due to a load 
varying from 0 to 20 kilogrammes. The deflexion due to hysteresis was observed 
(1) when no current flowed through the wire, and (2) when a current of definite 
strength flowed through the wire. The current w^as furnished l)y a single Daniell 
cell, and, judging from the last experiment, was about 1 ’3 amperes. In the table the 
last column shows the j^ercentage diminution of the hysteresis due to the passage of 
the current. The numbers in this column are rather irregular, but they show quite 
clearly that the effect of the current diminishes as the tension increases. The initial 
increase of W and its subsequent decrease, noticed in detail in § 52, are well shown 
in this ex23eriment. 
Tension 
(kilos.). 
Deflexion, 
current ofl’. 
Deflexion, 
current on. 
Diminution, 
per cent. 
0 
73 
55 
24-7 
4 
90 
76 
15-6 
8 
98 
82 
16-3 
12 
94 
82 
12-8 
16 
84 
74 
11-9 
20 
75 
67 
10-7 
§ 71. In concluding this paper we desire to express our thanks to Professor J. J. 
Thomson for his encouragement during the progress of the experiments, as well as for 
the use of the resources of the Cavendish Laboratory. We are also indebted to Mr. 
John Talbot, of Trinity College and to Mr. W. G. Frazer, Fellow of Queens’ 
College, for valualjle assistance during the earlier stages of the work, and to Mr. 
L. N. G. Filon, of King’s College, for help in connexion witli Appendix I. We have 
to thank Dr. li. S. Clay, of St. John’s College, for some heljJ in the preliminaiy 
ex})eriments. We gladly record our obligation to the writings of Mr. Oliver 
Heaviside, for it wms liy the method of operators, so fruitfully used by him, that Ave 
first obtained the complete theory of tlie method. Our thanks are also due to Mr. 
W. G. Pye and to Mr. F. Lincoln, the mechanical assistants at the Cavendish 
Laboratory, for help and advice on many occasions. Their mechanical skill has 
been of great service to us. 
