THK 



'SOUTH AFRICAN JOURNAL 

 OF SCIENCE: 



COMPRISING THE REPORT OF THE 



! SOOTH AFRICAN ASSOCIATION 



FOR THE 



ADVANCEMENT OF SCIENCE, 



191 6. 

 MARITZBURG. 



OFFICERS : 1916-1917. 



PRESIDENT. 

 Professor J. Orr, B.Sc, M.T.C.E. 



VICE-PRESIDENTS. 

 A. H. Reid, F.R.I.B.A., F.R.San.I. Prof. E. H. L. Schwarz, A.R.C.S., F.G.S. 



Professor W. N- Roseveare, M.A. H. E. Wood, M.Sc, F.R.MetS. 



HON. GENERAL SECRETARIES. 

 C. F. JuRiT2, M.A.. D.Sc, F.I.C., Agricultural Chemical Research Laboratory, Capetown. 

 J, A. FooTE, F.G.S., F.E.I. S., Commercial High School, Plein Street, Johannesburg. 



HON. GENERAL TREASURER. 

 A. Walsh, P.O. Box 39, Capetown. 



ASSISTANT GENERAL SECRETARY. 



H. Tlckek-, Cape of Good Hope Savings Bank Buildings, St. George's Street, Capetown. 

 P.O. Box 1497. (Telegraphic Address: "Scientific") 



EDITOR OF TRANSACTIONS. 

 Dr. C. ■^. JvRiTz. 



,VOL XIII. MARCH, 1917. NO. 8 



CAPE TOWN, 



PUBLISHED BY THE ASSOCIATION. 



1917. [Price 28. 



