5S8 The Trials of Light Portable Motors at Plymouth, 
Simpson, 
Strickland 
& Co. 
Dartmouth 
E. B. & F. 
Turner, 
Ipswich 
Summary of Boiler Eesults 
Adams & Co., 
Northampton 
Water evaporated per lb. of coal from"! 
8726 
7-65 
5978 
Equivalent evaporation from and at 212° 
10-42 
9-065 
7136 
Heat wasted per lb. of coal, in evaporaO 
4-70 
6 055 
7-984 
•689 
•599 
•528 
Thermal units transmitted per minute 
through each square foot of heating 
f 
59-42 
185-4 
150-1 
Coal burned per square foot of grate per " 
> 
9-635 
16-65 
12-75 
"Water evaporated per square foot of heat- " 
1 
3-09 
9-71 
7-80 
These figures tell their story very clearly. In Messrs. Adams 
& Co.'s engine, little more than half the heat of the coal was 
given to the steam, in Messrs. Turner's engine T ^-, while in 
Messrs. Simpson & Strickland's engine nearly was given 
to the steam. The figures for coal burned per square foot of 
grate per hour, and for thermal units transmitted per square 
foot of heating surface, show the reason of this. Messrs. 
Adams's boiler was forced, so that it had more than double the 
duty to do that Messrs. Simpson, Strickland & Co.'s had. Messrs. 
Turner's boiler was forced even more than Messrs. Adams's, but 
gives very decidedly better results. If, as is probable from other 
considerations, there was some priming with Messrs. Turner's 
boiler, the quantity of priming water carried over should be 
deducted from the apparent evaporation, and then the figure for 
their boiler would not be quite so high. 1 But no doubt it was 
chiefly the better arrangement of the heating surface in Messrs. 
Turner's boiler, and the reasonable care in clothing it to prevent 
radiation, to which its superior performance is due. x It is per- 
fectly absurd to use unclothed boilers. The clothing costs little, 
and adds little to the weight. The prevention of radiation 
means not only a saving of cost in coal, but it means also that 
a smaller and lighter boiler will do the required work with an 
equal efficiency. It showed a quite audacious contempt for the 
most obvious requirements of economical working to enter for 
competition a portable engine and boiler with all the boiler 
surface and steam pipes naked. 
1 If allowance is made for priming, Messrs. Turner's boiler result would 
be worse, but their engine result (consumption of steam per I.H.P. per hour) 
would be improved. Very possibly there may have been 10 per cent, of 
priming water in the steam from Messrs. Turner's boiler. 
