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ROYAL SOCIETY OF CANADA 



expansion, with an intended mean absolute admission pressure of 155 lbs. 

 and with 12-8 expansions. No. 26 indicates the number of the trial. 

 The following is a list of the trials to be described : — 



Trial Mark. 



155 



C Nos. 17, IS, 19, 20... 



12-8 



155 



T Nos. 21, 22,2(5 



12-3 



C Nos. 30,31 



12-3 



T Nos. 40, 41, 42, 43... 



12 3 



1.55 



T Nos. 28,29 



12 3 



205 



T Nos. 36, 37, 38, 39... 



22 



205 



Q Xos. 32, 33, 34, 35. . . 



■» 



Cylinders Used. 



2 and 4 



2, 3 and 4 . . 

 land 4...,. 

 1, 2 and 4 . . 

 1, 3 and 4 . . 

 1, 2 and 4. . 

 1, 2, 3 and 4 



Ratio of Cylinders used. 



1-9 : 7-7. 



1-9 : 4 4: 77. 



1 : 7-7. 



1:1-9: 7-7. 



1:4-4: 77. 



1:1-9: 7 7. 



1 : 1-9 : 4-4 : 7 7. 



AVith each of these cylinder ratios and initial pressures exj)eriments^ 

 have been made, with and without jacket steam on the trial cylinders,- 

 and in most cases at two speeds. 



Valve Leak Trials. 



In order to obtain the correct dryness fraction of the steam during 

 expansion it was necessary to ascertain if there was any leak past the 

 slide valve and if so to measure the amount of it. The experiments made 

 in this connection were carried out, it is thought, in a manner approach- 

 ing more closely the actual conditions under which the engine usually 

 works than any that have yet been published. In all other cases of 

 which the writer knows, steam has been let into the steam chest w^hilst 

 the engine was standing, and the steam that leaked past the valves into 

 the exhaust, collected and measured. It is quite certain that any results 

 obtained by this method could not be said to give an}' accurate indi- 

 cations of what really occurs whilst the engine is working. In these 

 trials, the steam ports of the particular cylinder upcm which the leak 

 test was to be made, were filled with lead plugs, hammered and caulked 

 so as to be steam tight. The exhaust pipe was taken oft" the cylinder^ 



