A steam corvette, to carry twelve guns, built for the Russian government by Wm. H. Webb, this city, was successfully launched on the 16th inst., with her propeller and a portion of the main shaft in place. It was feared that this heavy weight at the extreme end might spring her amidships; but not the least variation in her shear was perceptible after launching, thus demonstrating the great strength of her construction. Her extreme length is 214 feet; breadth of beam, 36 feet; depth of hold, 18 feet. Her engines, which are oscillators of 350 horse power, are now building at the Novelty Works, and they will bs fitted up during the winter. She will ba finished early in the spring, and proceed direct to the river Amoor. This, we believe, is the second steam vessel of war which has been built for the Russian government in New York. Thus it is, the New World is leading the Old. American divers are engaged to raise the sunken vessels at Sevastopol, and Americans build Russian railroads and steam vessels of war.