H, A. Rowland—Studies on Magnetie Distribution. 325 
This helps to explain the different results arrived at in the 
determination of the coefficient of contraction of different mus- 
i have 
cles. Thus, the following values in kers. per sq. cm. 
been found by various experimenters.* 
1. Flexors of arm, 8°99 (Henke.) 
7 “ “ Bhat 1 ais) 8d 8-1 “ 
; bs ee WES 6°67 (Haughton.) 
4, Extensors of foot, ----- 5°90 (Henke.) 
‘ * 6 Bas ee y 11°60 (Koster.) 
&. Mexors of legs... 223.6 7°78 (Haughton.) 
Haughton has pointed out other reasons for such differences, 
but one of the most important reasons is found in the amount 
of training which the muscle has received. Hence, muscles 
which are seldom called into action, have not the same con- 
tracting power as those which are daily used. 
_The experiments here described, as well as those before 
given in this Journal, were performed while I was an assistant 
in the laboratory of Prof. Gustavus Hinrichs, to whose kind- 
ness I am under many obligations. I also take pleasure in 
acknowledging experimental aid from Prof. W. C. Preston and 
Mr. D. A. Myers 
St. Louis, June 15th, 1875. 
—__ 
Arr. XLIL.—<Situdies on Magnetic Distribution; by Henry A. 
Row ann, of the Johns Hopkins University, Baltimore.t 
Part L.—Linear Distribution. 
ConTents.—I, Preliminary Remarks; II. Mathematical theory; III. Expe: i- 
Peutal methods for linear distribution; IV. Iron rods magnetized by induction ; 
V. Straight electromagnets and permanent steel magnets; VI. Miscellaneous 
applications. 
L 
to some 
the distribution of magnetism. It is with diffidence that I 
- coe this subject, being aware of the great mathematical 
T thought it would be well to publish them, particularly as it is 
Qo fault of mine that they did not appear some years ago.§ 
‘ Haughton’s “Animal Mechanics.” London, 1873, p. 70. 
D, Pp. . 
gem icated by the author. t Particularly M. Jamin. stunt 
All the experiments referred to in this paper were made in the win 
1870.71, 
