etallic
contraction of the enormous tubes is provided for by supporting them on
cannon-balls! how venerable seems the most graceful of Tuscan bridges,
when we remember it was erected in the fifteenth century,--and the
Rialto, when we think that it was designed by Michel Angelo! and how
signal an instance is it of the progressive application of a true
principle in science, that the contrivance whereby the South-Americans
bridge the gorges of their mountains, by a pendulous causeway of twisted
osiers and bamboo,--one of which, crossed by Humboldt, was a hundred and
twenty feet long,--is identical with that which sustains the magnificent
structure over the Niagara River! In a bridge the arch is triumphal,
both for practical and commemorative ends: unknown to the Greeks and
Egyptians, even the ancient Romans, it is said by modern architects, did
not appreciate its true mechanical principle, but ascribed the
marvellous strength thereof to the cement which kept intact their
semicircle. In Caesar's "Commentaries," the bridge transit and vigilance
form no small part of military tactics,--boats and baskets serving the
same purpose in ancient and modern warfare. The Church of old originated
and consecrated bridges; religion, royalty, and art celebrate their
advent; the opening of Waterloo Bridge is the subject of one of the best
pictures of a modern English painter; and Cockney visitors to the
peerless Bridge of Telford still ask the guide where the Queen stood at
its inauguration. But it is when we turn from the historical and
scientific to the familiar and personal that we realize the spontaneous
interest attached to a bridge. It is as a feature of our native
landscape, the goal of habitual excursions, the rendezvous, the
observatory, the favorite haunt or transit, that it wins the gaze and
the heart. There the musing angler sits content; there the echoes of the
horse's hoofs rouse to expectancy the dozing traveller; there the glad
lover dreams, and the despairing wretch seeks a watery grave, and the
song of the poet finds a response in the universal heart,--

"How often, oh, how often,
In the days that have gone by,
Have I stood on that bridge at midnight,
And gazed on the wave and sky!"

One of the most primitive tokens of civilization is a bridge; and yet no
artificial object is more picturesquely associated with its ultimate
symbols: the fallen tree whereon the pioneer crosses a stream in the
wilderness i