continuously for several days.

The following were the data for a day of 24 hours, with an interval of
half an hour: 8:55 P.M. one day to 8:55 P.M. the next, interval 8:30 to
9 A.M. Anthracite used, 18.4 cwt.; coke used, 3.42 cwt.; water used for
steam injection, 217.3 gallons; water used in scrubber, 4,106 gallons;
water used in cooling the cylinder, 20,000 gallons; oil used in
cylinder, 14.84 pounds; grease, 1.8 pounds; revolutions of machine,
142,157, or 100.8 per minute; effective work, 75.86 French horse power,
or 77.4 British; gas used, 6,742 cubic feet per hour, at 772 mm.
pressure and 70.7 deg. F., or 83.7 cubic feet per effective horse power;
efficiency, 69 per cent.

Now, with regard to the comparison between the large gas motors and
steam engines of the same size, M. Witz goes on to remark that the gas
engine is by no means, as was formerly thought on high authority,
necessarily restricted to the domain of smaller work and sizes. Even in
early times it was seen that the gas engine belonged to a type in which
there were possibilities of improvement greater than those available in
the steam engine, because the difference of temperature between the
working substance in its hotter and its cooler condition was greater
than in the steam engine; and consumptions of 5,250 cubic feet per horse
power per hour soon descended step by step as far as 2,060, while the
power went up, past 4, 8 and 12, to 25 or 50 horse power; and in the
exhibition of 1889 there were gas engines seen in which the explosion
chamber had a diameter of as much as 23 inches.

But the price of coal gas seemed to be too high for use in these large
engines, in which sizes steam is comparatively cheap; and so poorer gas,
which, though possessing only about 28 per cent. of the heating power,
is still cheaper in proportion than coal gas, when it is made on the
spot, was introduced to tide over the difficulty. Difficulties have been
successively overcome, with the result which we have just seen, namely,
1.37 pounds of anthracite per effective horse power, or about half the
carbon which a steam engine of the same power of excellent design, and
well kept up, would consume. A 50 horse simplex at Marseilles, in
Barataud's flour mill, is said to have run for the last 2 years on 1.12
pounds of English anthracite per effective horse power; and thus M. Witz
says his predictions of 10 years ago, that the gas producer would some
day replace the boiler, are being