NOTES ON STATIONARY ENGINES. 43 



given in actual or indicated horse-power, ratlier than by the 

 nominal, which it is to be hoped will bocomo obsolete in a 

 few years ; in fact, there is some probability that if the Board 

 of Trade or Lloyd's were to make a dead set aLjainat the 

 " nominal " horse-power, its days wonld bo soon numbered. 



The question of horse-power reminds one that it would 

 be well if every engine of size were to bo thoroughly tested 

 as to its power, economy, and capabilities generally. And 

 this shonld bo done in such a manner as to distingni.sh as to 

 the capabilities of the boiler quite separately from the 

 engine, and of any feed-heater (which may bo in use) 

 quite separately from either. This is comparatively seldom 

 done, though it has been shown, over and over again, how 

 it may be done with advantage. To class the wliole set of 

 engine, boilers, etc., together, and to speak of the economy 

 of the whole, is much like classing together several steam 

 vessels or locomotives, and when any defect is suspected, 

 taking no stops to separate the several perfoi'mancos with a 

 view to localise the trouble. Several pi'ivate firms and 

 boiler insurance companies now make a practice of testing 

 under a pr'oper system, amongst the for(!most of whicli may 

 be mentioned Messrs. Donkin and Messrs. Simpson, of 

 London. Such testing, if generally adopted, would be the 

 moans of disposing of many pet theories as to the economics 

 resulting from particnlai' modes of working, whieli, thongii 

 perhaps usually beneficial, are yet often very much over- 

 rated. For instance, a simple calculation will show that 

 about 20 per cent, of economy is about the most which can 

 bo obtained without actually raising steam in a fecd-hcater, 

 and this can only bo secured by most scrupulous attention to 

 detail throughout ; it is not however uncommon to hoar of 

 claims ranging up to 30 per cent., or even more, on account of 

 some such arrangement. This often results from a stoppage 



