Atlantic Monthly | Page 7

Stone bridges so rarely occur upon the roads of America, that they
hardly need remark. The Starucca Viaduct, by Mr. Adams, upon the
New York and Erie Railroad, and the viaduct over the Patapsco, near
the junction of the Washington branch with the main stem of the
Baltimore and Ohio Railroad, show that our engineers are not at all
behind those of Europe in this branch of engineering. From the civil let
us pass to the mechanical department of railroad engineering. This
latter embraces all the machinery, both fixed and rolling; locomotives
and cars coming under the latter,--and the shop-machines, lathes,
planers, and boring-machines, forging, cutting, punching, rolling, and
shearing engines, pumps and pumping-engines for the water-stations,
turn-tables, and the like, under the former. Of this branch, little, except
the design and working of the locomotive power, needs to be
mentioned as affecting the prosperity of the road. Machine-shops,
engine-houses, and such apparatus, differ but slightly upon different
roads; but the form and dimensions of the locomotive engines should
depend upon the nature of the traffic, and upon the physical character
of the road, and that most intimately, --so much, indeed, that the
adjustment of the grades and curvatures must determine the power,
form, and whole construction of the engine. This is a fact but little

appreciated by the managers of our roads; when the engineer has
completed the road-bed proper, including the bridging and masonry, he
is considered as done with; and as the succeeding superintendent of
machinery is not at that time generally appointed, the duty of obtaining
the necessary locomotive power devolves upon the president or
contractor, or some other person who knows nothing whatever of the
requirements of the road; and as he generally goes to some particular
friend, perhaps even an associate, he of course takes such a pattern of
engine as the latter builds, --and the consequence is that not one out of
fifty of our roads has steam-power in any way adapted to the duty it is
called upon to perform.
There is no nicer problem connected with the establishment of a
railroad, than, having given the grades, the nature of the traffic, and the
fuel to be used, to obtain therefrom by pure mechanical and chemical
laws the dimensions complete for the locomotives which shall effect
the transport of trains in the most economical manner; and there is no
problem that, until quite lately, has been more totally neglected.[3]
Of the whole cost of working a railroad about one third is chargeable to
the locomotive department; from which it is plain that the most proper
adaptation is well worth the careful attention of the engineer. Though it
is generally considered that the proper person to select the locomotive
power can be none other than a practical machinist, and though he
would doubtless select the best workmanship, yet, if not acquainted
with the general principles of locomotion, and aware of the character of
the road and of the expected traffic, and able to judge, (not by so-called
experience, but by real knowledge,) he may get machinery totally unfit
for the work required of it. Indeed, American civil engineers ought to
qualify themselves to equip the roads they build; for none others are so
well acquainted with the road as those who from a thorough knowledge
of the matter have established the grades and the curvatures.
The difference between adaptation and non-adaptation will plainly be
seen by the comparison below. The railway from Boston to Albany
may be divided into four sections, of which the several lengths and
corresponding maximum grades are as tabulated.

Length in miles. Steepest grade Boston to Worcester, 44 30 Worcester
to Springfield, 541/2 50 Springfield to Pittsfield, 52 83 Pittsfield to
Albany, 431/2 45
A load of five hundred tons upon a grade of thirty feet per mile requires
of the locomotive a drawing-power of 11,500 lbs.
Upon a 50 feet grade 15,500 lbs. Upon an 83 feet grade 22,500 lbs.
Upon a 45 feet grade 14,500 lbs.
Now, if the engines are all alike, (as they are very nearly,) and each is
able to exert a drawing-power of five thousand pounds to move a load
of five hundred tons from Boston to Albany, we need as follows:
B. to W.--11500/5000 or 2 engines. W. to S.--15500/5000 or 3 engines.
S. to P.--22500/5000 or 5 engines. P. to A.--14500/5000 or 3 engines.
From which the whole number of miles run by engines for one whole
trip would be,--
B. to W. 44 miles by 2 engines, or 88 W. to S. 541/2 miles by 3 engines,
or 1631/2 S. to P. 52 miles by 5 engines, or 260 P. to A. 491/2 miles by
3 engines, or 1481/2 ______ And the sum, 660
Now suppose, that, by making the engines for