02^ 'IRANSACTIONS OV SOCIKTI KS. 



ami uditli .side oi ijarl)crton Aiinintaiii, and tin.' distrilnuioii ni the meta- 

 murpliic rocks points to a contact belt up to about three miles wide. 

 Endomorpliic modifications within the granite itself are indicated by the 

 development of finer grained or gneissic structures, oriented with refer- 

 ence to the strike of the neighbouring older rocks. The distribution of 

 the granite margin round Hectorspruit strongly indica!tes an inclusive 

 relationship. Jt was therefore concluded that the- older granite had 

 intruded into both the Jamestown and Moodies Series. The Jamestown 

 Series probably represents originally a series of basic rock itself intrusive 

 into Moodies Series, and the metamorphisni of the latter might conceiv- 

 ably be due to the former rather tlian to the granite. 



Monday, May 21 : A. L.du Toit, B. A.. D.Sc.F.G.S., President, in the chair. 

 — ■■ The Dyke System of the De Kaaf and Koniali Rk-cy Valleys " : A. L. 

 Hall. Owing to their resistant nature the dykes stand out as conspicuous 

 and fairly straight ridges especially in the low-lying granite valleys. Out 

 of 1 10 dykes separately mapped, jS run from south-east to north-west 

 u\ er an area of country measuring 45 by 56 miles. They are usually from 

 20 to 50 feet across, but some are much thicker — up to 130 and even 200 

 feet. The bulk of these occurrences belong to the gabhro and diabase 

 families. The author concluded that the direction of alignment was pre- 

 determined by the intrusion of the older granite into the surrounding 

 rocks and the dykes Jiave no community of origin with the granite but 

 represent the dyke phase of the 1)asic margin of the Bushveld Complex, 

 and should be assigned to the group of aschistic dykes. — "Interesting 

 luii^nnitii- rocks from the Gordonia District. Cape Province '' : Dr. P. A. 

 Wagner. The rocks referred to occur on farms in the Southern Kalahari, 

 aljout 45 miles west-north-west of Upington. The most widely distributed 

 type of migmatic rock is a composite garnet-sillimanite-biotite-gneiss. 



Soiiii Akkican .'\s.soci.\Trnx of .\n.\lvtical Chemist.s. — Tuesday, 

 .\pril loth : J. McCrae, Ph.D.. F.I.C"., Vice-President, in the chair. — 

 '' f)em(instration of Hii^igiiis' and Maniott's method of determining carbon 

 dioxide in air": Dr. J. Moir. 'I he author demonstrated the method 

 used and pointed out its adapta))ilil\- in determining carl)on dioxide in 

 mine air. — "Some considerations on ferlility of soils": A. Baguley. 

 Tile autlior dealt shorth^ with the many considerations whicli seriously 

 affect soil fertility and gave a concise survev of the present theories. 



Tuesday. May Sth : J. McCrae. Ph. D.^ I'.l.C, Vice-President, in tlie 

 chair. — "The zvlnmetric estimation of zvater and water extracts" : \V. 

 Torrance. The author outlined an adaptation of tlie Pfeififer and Wartha 

 nirtliod as used at the Gtn-ernment School of .Agriculture. Grootfontcin, 

 i'<r the analysis of water and water e.xtracts. — '■ ./ note on the local manu- 

 facture of shoes and dies." : Prof. G. H. Stanley. The exi)eriniental 

 plant for the manufacture of shoes and dies from scrap was described and 

 details of the working of the electrical plant given. 



SoiTH Akkkav Sc.ciktv of {'\\i\. 1^\<,i\ki-;rs. — Wednesday. April iilli: 

 R. W. Memnuir, M.I.C.K., President, in t!ie chair. — " 'The Construction of 

 the Gamtoos-Patentie 2-feet naui^e raihcay." J. C. Simms. 'l"he question 

 iif opening up the fertile valley of the Gamtoos River had engaged the 

 attention of Government for 25 years, but the great cost of a railway along 

 the precipitous sides of the valley through hard conglomerate cliffs, inter- 

 sected by numerous narrow kloofs caused tjie imdertaking to be deferred. 

 In 191 1 the author received instructions tc) undertake the survey and 

 construction of a line as far as Patentie — a distance of 17 miles. The 

 detailed survey cost £95 per mile and the staking out of the centre line 

 £41 per mile. There are two major ])ridges over the line, one over the 

 (ieclhontboom Kloof, and one over the Klein River. The 17 miles of line 

 cost, when completed, £71,200. The line was completed in March, 1914. or 

 2N months after connnencement. — " Xotes on the construction of the 

 .Itiwal Korth-y.astron RaiTiCay '' : The author commenced construction of 

 the line in 1914. The length of the line is 55J miles, and the total cost of 

 the survey was £bj,.2 per mile of constructed line. The countrv traversed 



