PROCEEDINGS OF SECTION A. 195 
1 1 1 1 
: TG » 4 A Se as (az) oY. 
¥ Ss Be 6 1 
18. a" efi: Ga)} + 23 (; s) |ev. 
19. ea peer ee 
Py P2 
20) el +=y)d5 = s (ez)?” 
eee 
In 17 and the two following p; and p, are the principal radii 
of curvature at the point x, y, s; in 20 7 and 72 are the lengths 
of the semi-axes of the central section parallel to the tangent 
plane at x, y, z, and in 21 a is the length intercepted by the 
ellipsoid on the normal at x, y, z. 
pe 
~I 
t 
I take this opportunity of thanking Mr. R. J. A. Barnard, 
M.A., University of Melbourne, for his kindness in verifying 
the accuracy of the integrals in the preceding table. 
5—FLUID VISCOSITY AND ITS TEMPERATURE 
VARIATION. 
By R. Hosk1ne. 
(Printed in the “ Philosophical Magazine,” March, 1900.) 
6.—NOTE ON THE PERMEABILITY OF SAMPLES OF 
STEEL CAST IN MELBOURNE. 
By Witrrip N. Kernot, B.C.E. 
[Abstract with Plate ITT.) 
Tus object of this investigation is to determine the permeability 
of locally-manufactured cast steels with reference to their fitness 
for making dynamo fields and other similar magnetic structures. 
The tests were made on rings by the method of reversals, 
using a low resistance ballistic galvanometer. The magnetify- 
N 2 
