Permeability of Iron and Steel. 
J. Forged Ring Cast Steel (Soft). 
Mean diameter . . d@ =14'25 centim. 
Bar-thickness 2R= 1:421 _,, 
Number of coils. . » =1074. 
p calc. =120 + 340 sin 0, 
where 
é= Be degrees. 
i00. © 
It. Ie 
33. ere deesie 25—|he DUTT, 35. 
Obs. | Cale. Obs. | Cale. 
21°873| 126 121 — 5 5815-9 420 409 
83°360!} 120 125 + 5 9467°8 461 459 
2773 156 136 —20 11497 443 428 
1825:9 248 226 —22 12443 326 400 
2367-0 YAO 256 + 7 15352 154. 272 
35166 314 312 — 2 18597 90 85 
J. Forged Ring Cast Steel (Hard). 
Mean diameter . . d@ =14:25 centim. 
Bar-thickness 2R—= 1421 5. 
Number of coils. . 2» =1069. 
ucale.=45 + 90{sin 0+ sin 20}, 
where a3 
8= -— decrees 
100 °°8 
pl. p. 
fee | ite ae 
Obs. | Cale. | Obs. | Cale. 
Fem 491. 451) 4 645 | 67 | 62 
59°48 47 47 0 2189 | 115 110 
120°8 48 48 0 4492 150 153 
170°4 ed! 52 +] 6496 157 161 
267°9 i Oe 58 —4. 8959 134 135 
405 62 59 =3 13870 70 60 
551 64 62 —2 
First, as to the saturation-value. 
19 
In nearly all the rings of 
erown iron the saturation-value of the induction is under 
18,000, although in ring F it appears to exceed 19,000. This 
agrees generally with Rowland’s result as to rings. 
In my paper on Electromagnets (Phil. Mag. xvii. p. 532) I 
have shown that in the case of the two bars there examined 
the saturation-values were higher, and did not appear to give 
evidence of having any fixed limit. 
This seems intelligible 
