[ 65 ] 
V. Experimental Determination of Magnetic Induction in an 
Elongated Spheroid. By Prof. D. N. Mallik*. 
1. T~N" a paper on the magnetic induction in a spheroid 
A due to a coil carrying current (Phil. Mag. Oct. 1907), 
I proved that if M be the induction at any point of such a 
spheroid, / \\ 
M =^(l + 47rF)27nm 1+ V c l _ f 1 
= Ap, say, \ tr J 
.'. if B = total magnetic induction over the semi-ellipsoid, 
B = JMdS = AJNS = Aa*fa, 
= (l + 4:irk)2irmi\l— ^.jfex, nearly, 
where dS is an element of surface, and d# an element 
of the major axis ; 
. dB 
i.e. -j— = const. 
ax 
In this form it is suitable for experimental verification, 
and I have made a series of experiments to test its accuracy. 
A 
D r- 
Zcngth of rod... JO Cm 
Dia ??teter E-6 cm. 
2. For this purpose, a rod AB (fig. 1) was prepared 
* Communicated by the Author. 
Phil. Mag. B. 6. Vol. 15. No. 85. Jan. 1908. F 
