Trials of Traction- Engines at Wolverhampton. 549 
ruslicd tlii'ougli the gauge with great velocity, and no humouring of llic re- 
versing-handle or steam-cock would render the water quiescent. It was 
from this cause that it was impossible to leave off with the same amount 
of water as was in the gauge before starting. On the completion of the pre- 
liminary run the water was out of sight, and on the comi)ietiou of the final 
run it was also out of sight. We felt that so much time had been consumed 
upon the trial of this engine, that we should not be justified in working the 
preliminary run over again, with the hope that wlien it was done the water 
might be in sight, and with the still further hope that on the completion of 
the final trial the water might also be in sight. In order to test the facility 
with which the water could be pxit in motion through the gauge, we ordered 
the small blast-cock to be turned on while the engine was standing, and the 
draught of this small quantity of steam on the boiler was sufficient to cause 
the water to circulate in the gauge, and it was not until the blast-cock was 
half shut that the water would remain stationary. We found that the engine 
could not be run in the least expansion with the regulator open, as on 
attempting to do so the boiler primed excessively. 
If the description which has been given of the boiler has been intelligible 
in the absence of a sketch, it will be seen, that if the water-level happen to 
be coincident with the centre of one of the rows of nearly horizontal tubes, 
then, so far as regards that particular row of tubes, there is a very fair 
amount of surface for the delivery of the steam-bubbles generated in them ; 
but even then tlie lower rows would be compelled to discharge the whole 
of their steam, mingled with the current of water set up by the circulating 
tubes into the D pipes ; and assuming, as is quite possible, the water-level 
to be at such a heiglit as to be between some two rows of horizontal tubes, 
then the whole of the steam would have to escape from the water surface to be 
found in the three large and two small D-shaped tubes, being about an aggregate 
area of 2^ feet ; while the area of water surface in a locomotive boiler of similar 
power may be taken as 25 feet, or ten times as much. This circumstance is 
quite sufScient to account for the furious rushing of water through the water- 
gauge. 
liansomes, Sims, and Head's Q-Horse-power Farm Steamer. — The first 
engine in Group 4, was the 8-horse-power, No. 2149, of Messrs. Eansomes, 
Sims, and Head, price 750?. This engine, the " Sutherland," is of the " pot- 
boiler" and indiarubber-tyre construction, the invention of Mr. R. W. 
Thomson of Edinburgh. Piobably most of the readers of this Keport are by 
this time acquainted with the construction of the " pot-boilcr." Nevertheless, 
it may be well briefly to describe it here. It consists of a plain vertical 
cylinder, containing at its lower end an internal cylinder of lesser diameter, 
forming the fire-box. In the centre of the crown plate of the fire-box there is 
a circular opening, about 1 foot li inch diameter, to which is jointed the 
neck of the copper pot. Below the neck, the pot swells out into a spherical 
form, and is of such size as nearly to fill the fire-box, leaving, however, a 
S])ace of about 11 inch all round between itself and the inside of the fire-box. 
Up this space the products of combustion pass, and they make their escape 
from the fire-box through 36 vertical tubes IJ-inch bore, 3 feet lOi inches 
in length, which are inserted in the crown jjlate of the fire-box in the space 
left between its sides and the neck of the pot. These tubes extend through 
the upper part of the cylindrical case of the boiler to the top tube-plate ; they 
are surmounted by a short cylindrical casing or drum, from which rises the 
funnel. At the ordinary working height of the water, about 1 foot 6 inches of 
the tubes are immersed in the water, while 2 feet S-i inches of the upper part 
of the tubes aer in the steam space, thus drying and superheating the steam. 
The grate area is 5*25 square feet ; the total heating surface up to the level of 
the ordinary water-line is 80'5 feet ; the flue area through the tubes "66 of a 
