PROCEEDINGS OF SECTION A. 203 
77 = iW 
W 
0 
oe ai 
27a 2 
Suppose 4, = 16 x 
Lies Ag ~» 9 
se [168-314] {yu cose +r sin pol, : 
+ { pcos p (2 7—O)+v sing (27 20) Seay aa 
27 
= 
and we have 7’ = i 
The following table gives the ratio of the tension of a spoke 
in various positions to the weight of the rider when the initial 
tension of the spokes is half the weight of the rider :— 
) Ww 
0 .093 
10° .240 
20° 427 
30° 522 
180° | .522 
The practical result of the above investigation is that, with 
steel rim and spokes of the usual proportions, if the initial 
tension is about half the weight of the rider the spokes will 
always be in tension, and the tension of spokes at a greater 
angle than about 30° from the bottom is only very little 
increased above its initial value by the weight of the rider. 
1].—A POSSIBLE CAUSE OF THE EARTH’S MAGNETISM 
AND A THEORY OF ITS VARIATIONS. 
By W. SuTHERLAND, M.A. 
(Printed in “ Terrestrial Magnetism and Atmospheric 
Electricity,” June, 1900.) 
12.—THE TRANSFERENCE OF ENERGY THROUGH SPACE. 
By J. G. O. Tepper. 
