This book hinges upon the extraordinary adventures of a mad French inventor who has imagined a diabolical engine of war that in its explosive effects surpasses anything in this direction ever conceived by mortal man. The story is of a most exciting character throughout. It has an added and highly piquant interest from the fact that Turpin, the celebrated and excitable inventor, declared at the time of the first publication, that he has been libelled in the person of the mad hero of "Facing the Flag," and was bringing an action against Jules Verne. Turpin was the chemist who claimed that he discovered melinite (the explosive later used for shells in the French army and navy). The claim was denied by the military authorities. Turpin in his resentment published the formula of the explosive in a book, together with an account of his alleged wrongs, and drawings of certain mechanical inventions that the government desired to keep secret. For this he was thrown into prison, but owing to the persistent agitation kept up by the French press of all parties was released after several months' incarceration.