PREFACE «!S INTRODUCTION.
To THE I^XJBnUIO:
|N PRESENTING THIS CATALOGUE to the public it is our intention to illustrate ourline of work by engravings
taken directly from photographs of actual structures built by us. These illustrations are not pictures made to order to
show each bridge in the best possible light, but are all taken from photographs of actmn^WucruVes, just as they are.
We have endeavored to illustrate as many different kinds of bridges as possible, so that any party in want of a new iron
bridge can find something here which will show about how his bridge will look when completed.
The first iron bridges built in this country were made by Whipple, the compression members being cast-iron, and the tension members being wrought-iron. Many of these bridges are standing at the present day, notwithstanding their crude construction, and speak
much for the intelligence and honor of the builder. Cast-iron is, however, not well adapted for use in iron bridges, for no matter how well
and by what process the castings are made they are very apt to contain serious and unseen flaws, which only develop after breaking,
so that, at the present time, cast-iron, in bridge construction, except for minor details, has been almost universally abandoned. The first
bridges built by Whipple were built in a scientific manner, and, considering the limited knowledge of the subject at that time, reflect great
credit upon the designer. Since then but little progress has been made in the designing of iron highway bridges except in the matter of
detail, until the introduction of our Patent Parabolic Truss, which appeared in 1877 and 1878. This form of truss was a radical departure
from the old Whipple Truss, or the old Bow String Arch, which were in universal use until the Fall of 1877 or the Spring of 1878, and
the introduction of the Parabolic Truss at that time marks a new era in iron bridge construction.
The great object in an iron highway bridge is stiffness and simplicity. If the bridge is not stiff and rigid the traveling public get
an idea that it is weak and not fit for its work, and it is very soon necessary to replace it. Simplicity is required, because iron highway
bridges, after being once built, are seldom, if ever again, looked after, except, perhaps, occasionally to paint them. If the bridge is simple