The great chemist at once expressed his admiration; and when he had examined the mechanism and understood how the explosive was employed as motive power--an idea which he had long recommended,--he tendered enthusiastic congratulations to Guillaume and Thomas. "You have created a little marvel," said he, "one which may have far-reaching effects both socially and humanly. Yes, yes, pending the invention of the electrical motor which we have not yet arrived at, here is an ideal one, a system of mechanical traction for all sorts of vehicles. Even aerial navigation may now become a possibility, and the problem of force at home is finally solved. And what a grand step! What sudden progress! Distance again diminished, all roads thrown open, and men able to fraternise! This is a great boon, a splendid gift, my good friends, that you are bestowing on the world." Then he began to jest about the new explosive, whose prodigious power he had divined, and which he now found put to such a beneficent purpose. "And to think, Guillaume," he said, "that I fancied you acted with so much mysteriousness and hid the formula of your powder from me because you had an idea of blowing up Paris!" At this Guillaume became grave and somewhat pale. And he confessed the truth. "Well, I did for a moment think of it." However, Bertheroy went on laughing, as if he regarded this answer as mere repartee, though truth to tell he had felt a slight chill sweep through his hair. "Well, my friend," he said, "you have done far better in offering the world this marvel, which by the way must have been both a difficult and dangerous matter. So here is a powder which was intended to exterminate people, and which in lieu thereof will now increase their comfort and welfare. In the long run things always end well, as I'm quite tired of saying."