Trials of Traction- Engines at Wolverliamjdon. 555 
liansomes, Sims, and IIcad\ 'ti-IIorse-power, with Iron Wheels. — Group 5 
<;ontaiucd only one entry, viz. Messrs. Eansomes, Sims, and Head's (No. 2150) 
8-liorsc-power " pot boiler." 
This, as before stated, was the same engine (the " Sutherland ") as the entry 
No. 2149, but with cast-iron wheels in Wen of the indiarubber wheels, and 
with a difference in price of 250^. in consequence. 
The drivinp:-wheels, which were hollow cast iron disc-wheels, were 5 feet 
diameter b}' 1' 7f" wide. 
The steering-wheel was of cast-iron, the same construction as that of the 
driving-wheels, and was of the same dimensions as the indiarubber steering- 
wheel of the " Sutherland." 
There was, of course, no object to be attained in re-trjnng the " Sutherland " 
on the brake, under the guise of No. 2150, and thus there is no record to make 
of this entry as regards brake trials ; but it figured in a very uiteresting manner 
in a trial on the high road, to bo hereafter mentioned. 
General Kemaeks on Trials in the Yard. 
Having now described the various engines, we wish to say a few 
words on the evaporative duty of the boilers, on the desirability 
of steam-jacketing the engine cylinders, and on brakes on the 
driving-wheels. 
We were somewhat disappointed in finding the low evaporative 
duty of the boilers. In the best instance it was only 7"7G lbs. 
of water per 1 lb. of coal ; we had expected, at least, 1 lb. more of 
evaporation. Last year, at Oxford, from the old boiler of the 
Society as much was obtained in one instance as 9"35 lbs. of water 
per 1 lb. of coal ; and we had hoped that as good results would 
have been reached with the locomotive type of boiler in the 
traction-engine of Aveling and Porter, and of other exhibitors. 
In Aveling and Porter's engine. No. 7001, during the trial on 
the brake, the average temperature of the feed-water was from 
170 to 180 degrees. This may be the right time to remark upon 
the fact that when the feed-water is heated by actual contact 
with the waste steam, so that the steam which heats it becomes 
condensed and mingles with the water, no greater amount of cold 
feed- water is evaporated by the boiler than would have been 
evaporated had the water not been heated ; in fact, a slightly less 
amount is evaporated. A little reflection will make this clear. 
Although the feed-water may be heated, as in this case, 110 
degrees above the temperature at which it was supplied from the 
Society's tank, yet that heat is obtained from steam which becomes 
condensed and mingles with the water, and has itself to be re- 
cvaporated, and thus just so much more water from the steam 
has to be evaporated as would be equal to the saving in evapo- 
rating the feed-water by heating it, if the total of the latent and 
sensible heat of the steam in the boiler (say at 115 lbs.) were equal 
to the total latent and sensible and heat of the exhaust steam ; 
but as the total heat of the boiler steam is greater than that of the 
2 O 2 
