How isolated and bewildered are villagers, when, after a tempest, the news spreads that a freshet has carried away the bridge! Every time we shake hands, we make a human bridge of courtesy or love; and that was a graceful fancy of one of our ingenious writers to give expression to his thoughts in "Letters from under a Bridge." With an eye and an ear for Nature's poetry, the gleam of lamps from a bridge, the figures that pass and repass thereon, the rush and the lull of waters beneath, the perspective of the arch, the weather-stains on the parapet, the sunshine and the cloud-shadows around, are phases and sounds fraught with meaning and mystery. It is an acknowledged truth in the philosophy of Art, that Beauty is the handmaid of Use; and as the grace of the swan and the horse results from a conformation whose _rationale_ is movement, so the pillar that supports the roof, and the arch that spans the current, by their serviceable fitness, wed grace of form to wise utility. The laws of architecture illustrate this principle copiously; but in no single and familiar product of human skill is it more striking than in bridges; if lightness, symmetry, elegance, proportion charm the ideal sense, not less are the economy and adaptation of the structure impressive to the eye of science. Perhaps the ideas of use and beauty, of convenience and taste, in no instance, coalesce more obviously; and therefore, of all human inventions, the bridge lends the most undisputed charm to the landscape. It is one of those symbols of humanity which spring from and are not grafted upon Nature; it proclaims her affinity with man, and links her spontaneous benefits with his invention and his needs; it seems to celebrate the stream over which it rises, and to wed the wayward waters to the order and the mystery of life. There is no hint of superfluity or impertinence in a bridge; it blends with the wildest and the most cultivated scene with singular aptitude, and is a feature of both rural and metropolitan landscape that strikes the mind as essential. The most usual form has its counterpart in those rocky arches which flood and fire have excavated or penned up in many picturesque regions,--the segments of caverns, or the ribs of strata,--so that, without the instinctive suggestion of the mind itself, Nature furnishes complete models of a bridge whereon neither Art nor Science can improve. Herein the most advanced and the most rude peoples own a common skill; bridges, of some kind, and all adapted to their respective countries, being the familiar invention of savage necessity and architectural genius. The explorer finds them in Africa as well as the artist in Rome; swung, like huge hammocks of ox-hide, over the rapid streams of South America; spanning in fragile cane-platforms the gorges of the Andes; crossing vast chasms of the Alleghanies with the slender iron viaduct of the American railways; and jutting, a crumbling segment of the ancient