A Destructive Instrument of War,— Mr. S. R. Jenner of Crawford county, Ind., has shown us a shell invented by him which promises to prove a most destructive instrument of war- The shell is a compound one, being equal to five distinct missiles—or in other words is five distinct shells combined in one, fired by a single charge of powder, but doing all the execution oi five shells. Experiments were made with this shell this morning, at the foot of the Knobs, which proved it to be one of the moBt destructive and effective munitions of war ever invented.