Various plans have from time to time been formed, for giving strength
and security to bridges; the history of which, from the time when
streams were first crossed by rude logs or trees thrown over them, up to
the latest inventions, would be full of interest. One of the latest
improvements in this department, designed and invented by an ingenious
French engineer, M. Vergnais, is presented in the preceding cut. It was
originally intended to be thrown across the river Seine, at Paris. Some
years ago, a wire suspension bridge at Angiers gave way, while a body of
troops was crossing, precipitating an entire regiment into the water,
with a terrible loss of life. Since that dreadful catastrophe there has
always been a feeling of aversion in France, toward the erection of
suspension bridges. The ingenious improvement here presented is designed
to relieve all possible danger of breakage, and yet allow of the
construction of a bridge of gigantic proportions, without in the least
impeding navigation. In the ordinary suspension bridge, the main cables
sustain the entire weight, and should the connection between the bridge
and the cables give way, or either of the cables break, a most
melancholy end awaits all who have happened to be trusting their lives
to its security at the moment. In the application of Vergnais’s
improvement, the utmost security is afforded. A monster arch of iron is
thrown across from shore to shore. This arch is composed of such strong
materials as not to require great bulk, so that it presents an aerial
appearance. The flooring of the bridge is suspended from the arch by
innumerable pendants of iron, so that the weight of a body, in crossing
the bridge, is brought to bear gradually upon the structure, and when it
reaches the center, where common bridges are the weakest, under this
invention it reaches the strongest part, for it is directly beneath the
arch. Besides, should any of the pendants give way, the entire bridge
does not yield, for it is impossible for all the pendants to break at
once. This plan is certainly a new and novel one, so far as suspension
bridges are concerned. We hope that the inventor will be encouraged to
erect them in this country. Railroad companies will find them to be in
every way advantageous to their interest, since the cars may run across
them at the highest speed, with perfect security.