164* Proceedings, &&, for 1885. 



obliquity is considerable. Owing to this feature, again, there is 

 mathematically no dead point, and practically there is none on 

 account of the high speed. It is a proof of the remarkable per- 

 formances of this engine that one has run for five months at a 

 rate of 550 revolutions per minute, with only two stoppages of 

 fifteen minutes each. The Porter- Allen engine is a slight modifi- 

 cation of the older double-acting engines, and its chief feature is 

 the great care bestowed on the balancing of its parts, the weight of 

 which cannot be altered without diminishing the efficiency of the 

 engine. Edison has largely employed these engines for working 

 his dynamos, and one of them has been known to run for three 

 months at 350 revolutions per minute without stopping. The chief 

 contention of the advocates of the single-acting engines is that all 

 their parts are in compression, and that the wear and noise must 

 be at a minimum. This latter point does not seem to be realised 

 in practice, owing probably to the inertia of the rapidly-moving 

 parts. On the other hand, the supporters of the double-acting 

 system aver that there are really only two parts which can suffer 

 much from wear — viz., the pins of the connecting rod, and on the 

 fitting of these they bestow great care, besides attending very 

 carefully to the proportions and balancing of the moving parts. 

 Their strong point is that double as much work can be got out of 

 a double-acting as out of a single-acting engine. All things being 

 considered, it seemed probable that it was to the double-acting 

 system we must look for the best results in the future. 

 A short discussion followed the reading of the paper. 



29th April, 1885. 



The Secretary was unexpectedly detained, and was absent from 

 the meeting. No detailed minutes were taken. Two subjects were 

 on the notice paper — 



(1.) Mr. Rennick's paper on " Boiler Riveting." 



(2.) Mr. M'Lean, on " Long Shafting." 



The whole evening was taken up by the first paper, and the 

 discussion on it and the second paper had to be postponed to the 



27th May, 1885. 



Long Shafting. Mr. C. W. M'Lean, C.E. 



Sewage Systems. Mr. L. H. Chase, C.E. 



Professor Kernot explained that he had consulted with Mr. 

 Ellery as to the question which was brought up at the March 

 meeting of his retaining the chair of Section A. 



