country, and nowhere in the world has the
design and building of wooden bridges been carried to such
perfection and such extent as in the United States. We speak here of
structures built by such engineers as Haupt, Adams, and Latrobe,
--and not of those works, wretched alike in design and execution,
which so often become the cause of what are called terrible
catastrophes and lamentable accidents, but which are, in reality,
the just criticisms of natural mechanical laws upon the ignorance of
pretended engineers.

Among the finest specimens of timberwork in America are the Cascade
Bridge upon the New York and Erie Railroad, designed and built by
Mr. Adams, consisting of one immense timber-arch, having natural
abutments in the rocky shores of the creek;--the second edition of
the bridges generally upon the same road, by Mr. McCallum, which
replaced those originally built during the construction of the road,
--these hardly needing to be taken down by other exertion than their
own;--the bridges from one end to the other of the Pennsylvania
Central Road, by Mr. Haupt;--the Baltimore and Ohio "arch-brace"
bridges, by Mr. Latrobe;--and the Genessee "high bridge," (not a
bridge, by the way, but a trestle,) near Portageville, by Mr. Seymour,
which is eight hundred feet long, and carries the road two hundred
and thirty feet above the river, having wooden trestles (post and
brickwork) one hundred and ninety feet high, seventy-five feet wide
at base, and twenty-five feet at top, and carrying above all a
bridge fourteen feet high; containing the timber of two hundred and
fifty acres of land, and sixty tons of iron bolts, costing only
$140,000, and built in the short time of eighteen months. This
structure, if replaced by an earth embankment, would cost half a
million of dollars, and could not be built in less than five years
by the ordinary mode of proceeding.[2]

Further, the interest, for so long a time, on the large amount of
money required to build the embankment, at the high rate of railroad
interest, would nearly, if not quite, suffice to build the wooden
structure.

Again, our wooden bridges of the average span cost about thirty-five
dollars per lineal foot. Let us compare this with the cost of iron
bridges, on the English tubular plan, the spans being the same, and
the piers, therefore, left out of the comparison.

Suppose that a road has in all one mile in length of bridges. Making
due allowance for the difference in v