SECTIONAL TRANSACTIONS.— F, G. 3 J- 7 



surplus. Further, its determination implies that the risk rate is calculable. Finally 

 it may be questioned whether surplus profits shoidd be distributed. 



(7) Contributory co-partnership may be distinguished from the two preceding 

 schools. In itself it does not contain a complete theory. 



(8) Conclusion as to the place of co-partnership in industry. 



SECTION G. ENGINEERING. 



(Communications on Textiles, received at special sessions, will be found on p. 411.) 



(For references to the publication elsewhere of communications entered in the 

 following list of transactions, see p. 432.) 



Thursday, September 1. 



Presidential Address by Prof. Sir James B. Henderson on Invention 

 as a Link in Scientific and Economic Progress. (See p. 120.) 



Papers on Lubrication :— 



(a) Dr. T. E. Stanton, C.B.E., F.R.S.— The Lubrication, of Surfaces 

 under High Loads and Temperatures. 



The paper deals with experimental investigations carried out at the National 

 Physical Laboratory for the purpose of determining the thickness and arc of contact 

 of the oil film, and the nature of the frictional resistance of a cylindrical bearing when 

 the load is increased up to the seizing point. 



Apparatus for the measurement of the attitude and eccentricity of a cylindrical 

 half bearing is described, and the results obtained are compared with those calculated 

 from the theory. It is shown that the discrepancy between the observed and 

 theoretical results for high values of the eccentricity is due to the pressure in the oil 

 film at the extremity of the ' off ' side of the bearing becoming negative, as indicated 

 by the theory and the consequent drawing in of air into the space in the neighbourhood 

 of the ' off ' side with the result that the arc of contact rapidly diminishes. 



This, it is concluded, is the condition which brings about seizure of the surfaces at 

 loads considerably below those which would be expected from the theory. 



Apparatus is also described for the determination of the values of the frictional 

 resistance of the bearing as the temperature of the film is increased, and it is shown 

 that for every lubricant there is a well-defined temperature of minimum friction and 

 temperature of seizing. 



The results of experiments with various lubricants are discussed, and it is shown 

 that for bearings under very high pressures and temperatures the best performance 

 is not necessarily given by lubricants having the least co-efficient of friction for 

 surfaces in contact, i.e. under boundary lubrication conditions. 



{b) Sir W. B. Hardy. 

 Followed by Discussion. 



Prof. W. Cramp. — A Hydraulic Model illustrating the Behaviour of the Arc. 



The electric discharge, whether in the form of a spark, the current through a neon 

 tube, an ordinary arc, or a vacuum arc lamp, has one characteristic which distinguishes 

 it from conduction of other kinds. No current passes across the arc until a certain 

 maximum pressure has been reached, but after this the current can bo maintained by 

 a very much lower p.d. In some cases, the slope of the p.d. current characteristic is 

 negative ; in others, as, for instance, the neon tube, it is positive. Special forms of 

 discharge, such as the Poulsen arc, have a characteristic intermediate between that 

 of the neon lamp and that of the ordinary arc. The fact that the discharge p.d. 

 may be much lower after the current has once begun than at the time of breakdown, 

 enables the discharge, in its various forms, to produce surges and oscillations, provided 



