VERGNAIS’S IMPROVED BRIDGE.
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.