would not have occurred to any one to use anything else
but steam to effect the transformation.

The progress that has been made during the last twenty years in the
thermatic study and construction of gas motors (without speaking of hot
air motors) has shown that the use of steam is not absolutely
indispensable for the production of work, and it has demonstrated that,
as regards dynamic product, the gas motor preserves the advantage,
although the relatively high price of the illuminating gas employed in
the production of the motive power generally renders the use of this
combustible more costly than steam, especially for high powers.

The economic truth of twenty years ago, when gas motors absorbed 1,500
liters per horse hour and exceeded with difficulty an effective power of
from 8 to 10 horses, has become less and less certain, when the
consumption has successively descended to 1,200, 1,000, 800 and even to
600 liters of gas per horse hour, the power of the motors rising
gradually to 25, 50 and 100 horses with a motor having a single cylinder
of a diameter of 57 centimeters.

[Illustration: FIG. 1.--CORLISS ENGINE AND BOILER OF 100 INDICATED
H.P.--ELEVATION AND PLAN.

A, cylinder; B, condenser; C, boiler; R, feed water heater; D, chimney.]

But these results did not suffice, and it was desired to do better still
by dispensing with the use of high priced illuminating gas. An endeavor
was made to obviate the difficulty by manufacturing a special gas for
the motive power, as steam is produced for the same object, by
distilling coal, carbureting air, producing water gas by the Dowson
process, and by other equivalent processes.

The strides made in this direction were finally crowned with success,
and the results obtained in the recent experiments due to Mr. Aime Witz,
an undoubted authority in the matter, permit of affirming that now and
hereafter, in many circumstances, a gas generator supplying a gas motor
will be able to advantageously dethrone a steam boiler supplying a steam
engine of the same power.

These conclusions, which tend to nothing less than to limit the reign of
the steam engine, are confirmed on the one hand by an experiment carried
on for the last two years in the Barataud flour mill of Marseilles,
where a 50 h.p. "Simplex" motor has been running day and night for
several months without stopping, and consuming but about 500 grammes of
English anthracite per effective horse hour, and, on another h