SttcriON 111., 1896. [ 127 ] Ti;ans. R. S. C 



IX. — An Investigation to Determine the Relative Efficiencies of Multiple- 

 Expansion Engines. 



By A, L. Mellanby, 



Royal (18.51) Exhibition Scholar, Durham College of Science. 



(Communicated by Dr. Bovey, and read May 19, 1896.) 



Within late years several series of experiments have been made upon 

 compound and triple expansion engines working under different conditions 

 of initial pressure, number of exjDansions, and niimber of revolutions. 

 Chief among these have been the experiments of the late Mr. Willans, 

 carried out upon his well known type of central valve engine, and those 

 by Professor Osborne Eeynolds upon the experimental engines at Owen's 

 College, Manchester. 



As yet however, so far as the writer knows, none have been publish- 

 ed including the quadruple-expansion engine in the series. It is hoj^ed 

 that the following account of trials made in the Engineering Laboratory, 

 at McGill University, under the supervision of Professor Nicolson. will 

 form an acceptable addition to the literature dealing with steam engine 

 experimenting ; as they not only extend the series b}' including the 

 quadruple-expansion engine but afford results from a tj-pe of engine 

 somewhat different from those used by the above mentioned experimenters. 



The objects of the investigation may be classified as follows : 



1. To ascertain the relative etficiencies of engines working with compound 



or triple expansion under the same conditions of initial pressure, 

 revolutions and total number of expansions. 



2. To ascei"tain the relative efficiencies of triple and quadruple-ex^Jansion 



engines, working under identical conditions. 



3. To determine the effects upon economy, of varying the cylinder ratios 



in compound and triple-expansion engines working under identical 

 conditions. 



4. To determine the relative efficiencies of the same triple expansion 



engines, working at the same speed of revolution, but with different 

 initial pressures and total number of expansions. 



These investigations have been carried out upon the experimental 

 engine stationed in the McGill University Engineering Laboratory. 



By reference to (Fig. 1) it will be seen that the engine is of the 

 vertical type and has four cylinders which will, for convenience during 

 the remainder of this paper, be alluded to as cylinders 1, 2, 3 and 4. 



