SECTIONAL TRANSACTIONS— F. G. 459 



rate of increase in total income two years previously. The four equations, 

 when solved, involve cyclical fluctuations in income and investment with 

 an eight-year period. 



SECTION G.— ENGINEERING. 



Thursday, August 18. 



Presidential Address by Prof. R. V. Southwell, F.R.S., on The 

 changing outlook of engineering science (lo.o). (See p. 163.) 



Short Papers by junior engineers (11.30). 



Mr. D. G. Christopherson. — Relaxation method for the solution of 

 Poisson's Equation. 



Mr. J. R. Green. — Relaxation applied to calculate the flow of a com- 

 pressible fluid. 



Mr. F. B. Greatrex. — Transients in transformers {Oscillograph 

 demonstration). 



Mr. J. E. M. Coombes. — Suppression of radio interference caused by 

 trolley buses. 



Afternoon. 

 Visit to works of Messrs. Kryn and Lahy, Letchworth (Steel castings). 



Friday, August 19. 



Mr. R. W. Allen, C.B.E. — Some experiences of the use of scale models in 

 general engineering (lo.o). 



The paper provides instances of the application of the well-known 

 technique of investigation by means of scale models to general engineering. 

 The purposes and scope of model testing are surveyed with particular 

 reference to the design of centrifugal pumps, fans and the fluid conveying 

 passages generally associated therewith. Three examples taken from 

 centrifugal pump design and one from the design of fans are mentioned in 

 some detail, as are three instances of fluid passage problems. Of these 

 latter, two instances are of channels for conveying water, while the third is 

 a reference to an extensive investigation into the supply of forced draught 

 air to ships' boiler rooms. Attention is drawn to the close hydraulic 

 connection between the design of centrifugal and propeller water pumps 

 and the corresponding fans for displacing air. It is also pointed out that 

 the term scale model comprises the scaling of physical properties as well as 

 of linear dimensions. These considerations are illustrated by an account of 

 a technique recently developed for the testing of water pumps by the use 

 of air as a working fluid. The paper concludes with references to applica- 

 tions of scale models in other branches of general engineering. 



Discussion by Mr. E. F. Relf, Prof. C. M. White, and Dr. J. P. Gott. 



