S^(^ DJSt'KIMlXATKjX dl' 1 HE CONIC. 



through pairs of points on the conic and circle where the slopes 

 are identical. h>(jm symmetry they must, therefore, be the axes. 



Asymptotes of Hyperbola. — Since the asymptt)tes pass 

 through the centre their equalion. deduced from ^14), must be 



L i V + [ .r ) + ^ V Ir —ah x\ [ {y + J ^^ — I V h'—ob .r J = o. 



(20) 

 that is as- + 2 li.ry + hy- == o. (21) 



TRAXSACTJOXS OF SOCIETIES. 



Sdi'TH African Society (if Ci\'ij- Encinefrs. — \Veilnescla\-. October 

 13th : R. W. Alenmuir, A..M.1.C.E., Vice-President, in the chnir. — " The 

 appticatioii of reinforced concrete to small conduits for iniiiation pur- 

 poses": J. C. Hawkins Tlie author describee! the design and con- 

 struction, and furnished particulars with regard to the costs of furrow- 

 linings, t^umes, and siphons constructed in reinforced concrete, in the 

 Gamtoos River Valley, Division of llumansdorp. Cape Province. 



Sb'uTH' African iNSTrriTiox of Engtnerrs — Saturday, Feb- 

 ruary t2th : W. Ingham, .M.I.C.E.. .M.l.Al.E., President, in the chair. — 

 "Belt Conveyors" : A. Robertson ^nd A. AlcA. Johnston. The 

 authors discussed the transport of materials by means of endless bands 

 and their accessories, and, in particular, the handling of specihc materials 

 taken from gold and base metal mines which have to be transported in 

 accordance with established mining j^ractice, and to suit locnl and climatic 

 conditions. — "A pre-lieated blast cnpola": J. A. Parsons. A type of 

 cupola was described in which the- air blast, instead of lieing cold when 

 coming into contact with the ci>lumn of coke which is ordinarily placed 

 within the furnace on tiie kindling wood, is passed through a series of 

 tulcs in the top cr chimney of cupola, and reaches the coke bed, 

 after the lilast has been on for some twentv minutes, at an increased 

 temperature over one-third of the total temperature to be imparted to the 

 iron. It was claimed that such a cuitola economised coke, improved the 

 quality of the metal, prevented by the slagging up of the tuyeres, permitted 

 of a temporary holding up of the furnace, w-as cheap and easy to manu- 

 facture, and ))iissessed a cai)acit\- nuich in excess of that of the ordinar.v 

 cupola. 



SorxH African IxsTrri'TF of Ei.kcirical Enginkf.rs. — Thursday, 

 February Jjth : Prof. W. Buch.anan. M.LE.E , President, in the 

 chair. — Presidential address: Prof. \V. Buchanan. A review was 

 given of the life and work of Lord Kelvin, with personal recollections of 

 his activities in the science and practice of electricity. 



Chemical, Metat.lurcical an'd AIixing Society of South Afric.v. — 

 Saturday, February 19th: J. E. Thomas, A.I.M.M.. M.Am.LE.E., Presi- 

 dent, in the chair. "The conglomerates of the IVitzuatersrand " : Dr. E. T. 

 Mellor. The geological features of the Witwatersrand were compre- 

 hensively described in their bearing u]ion the conditions of deposition of 

 the gold-bearing conglomerates, considerable attention being devoted to 

 the sedimentary features of the conglomerates, their probable mode of 

 origin and their relation to the other portions of the Witwatersrand 

 system. The author proceeded to discuss the origin of the gold and its 

 distribution within the conglomerate beds and throughout the Witwaters- 

 rand system. In conclusion, the author considered the bearing of his 

 deductions on economic cmestions connected with the conglomerate, par- 

 ticularly in the Eastern Rand, which he held to be the most important 

 goldfield at present awaiting development. 



