Minutes of Proceedings. 
vii 
E. Jacot, W. E. Malherbe, were elected members. 
The following communications were made : — 
" Note on a Theorem of Ph. Gilbert, regarding the Differentiation 
of a Special Jacobian," by Thomas Muir. 
" Note on Kosanes' Functions, resembling Jacobians," by Thomas 
Muir. 
" The Triple Stellar System ^ Virginis and S 1757," by E. T. A. Innes. 
These two stars, although a considerable distance apart, constitute a 
system as they are moving through space with almost identical velocities 
and directions. 
"A Curious Mosquito," by G. A. H. Bedford. 
" On the Porosity of the Eocks of the Karroo System," by A. L. 
DU TOIT. 
Determinations are given of the porosity of over 90 rocks, the majority 
being from borehole cores. It was found with the threefold division of 
the Beaufort beds the mean porosity of the sandstone was 2-9 % for the 
lower, 5'2 % for the middle, and 5-5 % for the upper division. The figures 
for the Transvaal phase of the Karroo were much higher. The effects of 
weathering in increasing the porosity are discussed and analysed. 
" A Note on the Temperatures of the Air observed at Mochudi," by 
J. E. Sutton. 
The Note gives a brief account of some points of interest in the results 
of temperature observations by Harbor at Mochudi in the Bechuanaland 
Protectorate. The extremes of temperature are considerable, the greatest 
range so far observed being from 108° F. to 28° P. The mean maximum 
temperatures depend upon the sun's meridian altitude in much the same 
way as they do at Kimberley. The annual cold wave of the middle of 
July is felt at Mochudi like it is elsewhere further south. 
Ordinary Monthly Meeting. 
May 20, 1914. 
The President, Dr. L. Peringuey, was in the Chair. 
The Minutes of the previous Meeting were confirmed. 
The Hon. General Secretary announced that Professor E. B. Young, 
Johannesburg, had been nominated for Fellowship. 
The following were nominated for election as Members : — A. G. 
Howitt, p. Battaerd, H. Pealing, P. L. Sandes. 
The following were elected Members : — J. B. Lester, A. E. Thomson, 
J. Petersen, W. S. Webber. 
