On Compound Engines for Agricultural Purposes. 667 
Ironworks' engines at Cardiff in 1872, workinj» at the same 
pressure. We must answer that it may be hard work for the 
compound engine to beat in such a competition. Possibly it 
would not ; but it must be remembered that those results were 
obtained with elaborate expansion-gear, which would be inad- 
missible for traction and ploughing engines, and is rarely 
adopted even now in the portable engine. Moreover, those 
results were obtained when the engines were new, and practically 
in perfect order. If competitive trials were renewed after each 
engine had worked a twelvemonth without overhaul, the com- 
parative results would probably be greatly to the advantage of 
the compound engine, as the expansion-gear in the simple 
engine would probably have suffered and be out of adjustment ; 
while if any steam did leak past the first piston and slide-valve 
of the compound engine, there is every chance that the loss 
would be nearly regained in the low-pressure cylinder. 
• 
VOL, XVII — S. S. 
