es; as the
latest glory of centuries of patient observation, profound study and
accumulated skill, gained, step by step, in the never-ending struggle
of man to subdue the forces of nature to his control and use.

In no previous period of the world's history could this Bridge have
been built. Within the last hundred years the greater part of the
knowledge necessary for its erection has been gained. Chemistry was
not born until 1776, the year when political economy was ushered into
the world by Adam Smith, and the Declaration of Independence was
proclaimed by the Continental Congress, to be maintained at the point
of the sword by George Washington. In the same year Watt produced his
successful steam engine, and a century has not elapsed since the first
specimen of his skill was erected on this continent. The law of
gravitation was indeed known a hundred years ago, but the intricate
laws of force, which now control the domain of industry, had not been
developed by the study of physical science, and their practical
applications have only been effectually accomplished within our own
day, and, indeed, some of the most important of them during the
building of the Bridge. For use in the caissons, the perfecting of the
electric light came too late, though, happily, in season for the
illumination of the finished work.

This construction has not only employed every abstract conclusion and
formula of mathematics, whether derived from the study of the earth
or the heavens, but the whole structure may be said to rest upon a
mathematical foundation. The great discoveries of chemistry, showing
the composition of water, the nature of gases, the properties of
metals; the laws and processes of physics, from the strains and
pressures of mighty masses to the delicate vibrations of molecules,
are all recorded here. Every department of human industry is
represented, from the quarrying and the cutting of the stones, the
mining and smelting of the ores, the conversion of iron into steel by
the pneumatic process, to the final shaping of the masses of metal
into useful forms, and its reduction into wire, so as to develop in
the highest degree the tensile strength which fits it for the work of
suspension. Every tool which the ingenuity of man has invented has
somewhere, in some special detail, contributed its share in the
accomplishment of the final result.

"Ah! what a wondrous thing it is
To note how many wheels of toil
One w