indicated horse power (which was the maximum power of the engines
removed) should be maintained during the trial on a consumption of
1.25 lb. of coal per indicated horse power per hour. Originally the
boilers of the Ohio, from which this power was produced, were three in
number, double ended, 12 ft. 6 in. in diameter by 17 ft. 6 in. in
length, having each six furnaces 3 ft. in diameter, or eighteen
furnaces in all, with an aggregate fire grate area of 300 square feet.
The new boilers, fitted with the forced draught, are likewise three in
number, but single ended, 13 ft. in diameter by 11 ft. 2 in. in
length, having each three furnaces 3 ft. 3 in. in diameter, or nine
furnaces in all, with an aggregate fire grate area of 112 square feet.
Air for combustion is supplied to the boilers by one of Messrs. W.H.
Allen & Co.'s fans, 5 ft. 6 in. in diameter, driven direct by an
engine having a cylinder 7 in. in diameter with stroke of 4 in. The
boilers removed had two stoke holds across the ship, one fore and one
aft of the boilers, while the new boilers have only one stoke hold on
the after side. The engines removed have cylinders 57 in. and 90 in.
in diameter by 48 in. stroke, while the new engines have three
cylinders 31 in., 46 in., and 72 in. in diameter respectively, with
piston stroke of 51 in.

During the trials the coals were weighed out under the supervision of
the officers of the company, who also took the record of speed and
other data. After running down Channel for a considerable time, the
trial on the coals weighed out began, and lasted 4 hours 10 minutes,
during which time 10,885 lb. of Welsh coal were burned, the trial
ending with the same revolutions of engines and the same pressure in
boilers with which it began. The mean indicated horse power,
calculated from the mean of seven sets of indicator cards, taken
during the trial, and the mean revolutions per minute, found by