<64 TlIR.MITl-: ?:C()NOMY. 



off their wings before attempting- to influence a male, and wlien 

 attracted, the male also dealates and seeks his spouse on foot. 

 In the case of others, the female attaches herself to a prominent 

 •object, clinging head downwards, some kinds resting quietly, 

 as if content in the strength of their special aroma, an.other 

 violently agitating the wings, as if conscious of the weakness of 

 its aroma, and the desirability of aiding its distribution. 



In all cases the male insect, upon first meeting the female, 

 ■combs her caudal aj^ex with his mouth i)arts; then in nearly all 

 •cases dealation takes place. 



With two species, however, the wings of the male are dis- 

 'Carded, and the female flies off a short distance with him clinging 

 tenaciously to her abdomen. In every species it is the female that 

 directs all movements subsequent to these unconsummated nup- 

 tials. She leads the way by the shortest route to the ground, 

 the male following her closely behind, and she then selects the 

 site where the two burrow into the earth tosretlier. 



TRAXSACTIOXS OF SOCIETIES. 



South African Institution of. Engineers. — Saturday, April loth: 

 E. J. Way, A.M.T.C.E., Presick^it, in the chair. — " The status of an cugi- 

 jiccr" : J. B. Roberts. Tlic author discu.ssed the position and functions 

 •of engineerintf societies, and compared their activities with those of 

 other professional societies. 1 lie mining regulations m force in the 

 Union were commented oi;, i'.nd tlie requisite training for the engineer 

 l)riefly considered. 



Saturday, May 2yth : !■.. J. Way. A.M.I.C.E.. President, in the chair. — 

 "The Iiifluciice moisture in the air has on mine ventilation" : A. C. 

 Whittome. The author einpliasised the need of provision being made at 

 every working place for a sufficient weight of oxygen to ensure an 

 atmosphere suitable for breathing, and tlie necessity of attention l)cing 

 given to the modification of requisite volume involved in varying density 

 and atmospheric humidity. It was suggested that medical investigation 

 should be made into the effects on human beings of («) the inhalation of 

 varying volumes of air, consequent on change of pressure and temperature, 

 in order that the requisite weight of oxygen shall reach the lungs; (5) 

 the further modification of these volumes by the presence of a saturating 

 amount of water vapour; and (c) the condensation in the hmgs of watei" 

 .vapour from air at a temperature considembly liigher than tlie body 

 temperature. 



Geologtc.\l Society of South Africa. — Monday, April 19th : Prof. 

 R. B. Young, M.A.. D.Sc, F.R.S.E., F.G.S., Vice-President, in the chair.— 

 ^' Notes on a graphic intergro7vth of Diotsidc and Ihiienifc finni the 

 ■Benihesi Diamond Field. Southern Rhodesia": A. M. McGregor. A 

 mixture such as that described i.i fairly common in the concentrates left 

 lay prospectors. — "Notes on the occurrence of radioactive minerals in 

 South Africa": Dr. A. W. Rogers. The first group of radioactive 

 minerals described from South Africa seems to have been the monazite 

 and substances allied to euxenite and fergusonite from Emliabaan •'! 

 Swaziland, described by Dr. G. T. Prior. A mineral resembling the 

 •euxenite has been found in the course of geological survey work in Ken- 

 liardt. Radioactivity has also been found associated with specimens of 

 columbite and tantalite from Little Namaqualand. ^^lonazite, the com- 

 mercial source of thorium anrl cerium, has been found in South Africa 

 •only in Swaziland and on the farm Houtenbek, 60 nnles north-east of 

 Pretoria. 



