The steam engine familiarly explained and illustrated; with an historical sketch of its invention and progressive improvement; its applications to navigation and railways; with plain maxims for railway speculators. By the Rev. Dionysius Lardner ... With additions and notes by James Renwick ...

LOCOMOTIVE ENGINES ON RAILWAYS. 191
coke, then, to be equivalent to coal, ton for ton, this would
add.162 to the original estimate.
These several discrepancies being allowed for, and a proportional amount being added to the original estimate, the
amount would be raised to.601 of a penny per ton per mile,
which is within one-fortieth of a penny of the actual cost.
This difference is considered to be sufficiently accounted for
by the wear and tear produced by the very rapid motion,
more especially when it is considered that many of the engines were constructed before the engineer was aware of the
great speed that would be required.
"What then," says Mr. Booth, in the Report already
alluded to, "is the result of these opposite and mutually
counteracting circumstances? and what is the present position of the company in respect of their moving power? Simply, that they are still in a course of experiment, to ascertain
practically the best construction, and the most durable materials, for engines required to transport greater weights, and
at greater velocities, than had, till very recently, been considered possible; and which, a few years ago, it had not entered into the imagination of the most daring and sanguine
inventor to conceive: and, farther, that these experiments
have necessarily been made, not with the calm deliberation
and quiet pace which a salutary caution recommends,making good each step in the progress of discovery before
advancing another stage,-but amid the bustle and responsibilities of a large and increasing traffic; the directors being
altogether ignorant of the time each engine would last before
it would be laid up as inefficient, but compelled to have engines, whether good or bad; being aware of various defects
and imperfections, which it was impossible at the time to
remedy, yet obliged to keep the machines in motion, under
all the disadvantages of heavy repairs, constantly going on during the night, in order that the requisite number of engines
might be ready for the morning's work. Neither is this great
experiment yet complete; it is still going forward. But the