The invention of the double-acting engine, in which the impulsion of the steam is felt both in driving the piston forward and in forcing it backward, both upward and downward, the application of its force through crank and fly wheel, the creation of an automatic system of governing its speed, and the discovery of the economy due to its complete expansion, were all improvements of the first magnitude, and of the greatest practical importance; and all these were in rapid succession brought into existence by the creative mind that had apparently been brought into the world for the express purpose of giving to the hand of man this mighty agent, to perfect the mightiest power that mind of man has yet conceived. But to do the rest required more than inventive genius and mechanical skill. It demanded capital and the stored energy of labor and genius in other fields, directed by the mind of a great "captain of industry." This came to Watt through Matthew Boulton, a manufacturer of Birmingham, whose father and ancestors had gradually and toilsomely, as always, accumulated the property needed for the prosecution of a great business. The combination of genius and capital is always an essential to success in such cases; and good fortune, a Providence, we may well say, brought together the genius and the capitalist to do their work, hand in hand, of providing the world with the steam engine. Hand in hand they worked, and all the world to-day, and the race throughout its future life, must testify gratitude for the inexpressible obligations under which these two men have placed them, doing the work of the world.