The Trials of Light Portable Motors at Thjmouth. 585 
siderable. The temperature in the chimney towards the end 
of the trial was very high, showing very great loss from inade- 
quate heating surface. The boiler had double safety valves with 
weights and levers. 
General dimensions of steam engines tested 
Simpson, 
Strickland &, Co., 
Dartmouth 
E. R. & F. 
Turner, 
Ipswich 
Adams oc Uo., 
Northampton 
3492 
3496 
3487 
Nominal horse-power 
3 
5 
16 
36^ 
54 
J? 1 AA 
X.1UU 
toi loi. 
Engine 
/ 3-012 "1 
\5999 J 
Diameter of cylinder, inches . . 
4496 
7-010 
Stroke, inches 
6 
75 
10-0 
Effective area oi piston, square 
inches : — 
713 
IB* 876 
38*60 
■$■69 
15-275 
37 36 
2782 
„ bottom 
27-40 
/ 12-88 \ 
V.26-G0/ 
1 S-7 
T45-61 1 
Declared steam pressure, lb. per"! 
120 
65 
75 
square inch j 
Declared revolutions per minute . 
300 
220 
140 
Boiler 
Grate area, square feet .... 
2-4 
2-63 
4 7 
Total heating surface, square feet 
65-3 
34 5 
45-9 
Superheating surface, square feet 
25-2 
Weight of water at normal level,") 
"> / 
373 
1 The clearance was given by the makers as 20 cubic inches. But the 
diagrams show it must have been much greater than this. It has been taken 
in calculation at 12 per cent, of the cylinder volume. 
Mode of carrying out the trials. — For the purpose of the 
trials each engine was provided with a flat rimmed pulley on 
which a rope brake was arranged, having a dead weight at one 
end and a spring balance at the other. The pulley, under the 
advice of the Society's Engineers, had in all cases been made 
with a trough-shaped rim 2 in which water cculd be placed. The 
dead load was kept constant throughout the trial, and the spring 
balance read every ten minutes. The makers had also provided 
indicator gear, that of Messrs. Turner being quite satisfactory, 
while that of Messrs. Adams was too crude to be quite trust- 
Worthy. Tha diagrams throughout the trials were taken very 
* A plan first adopted by Mr. Druitt Halpin. 
VOL. I. T. S. — 3 Q Q 
