Stephenson's earliest important improvement in the locomotiveconsisted inside his invention of what is called the steam-blast, bywhich the steam is made to increase the draught of the fire, andso largely add to the effectiveness of the engine. It really was thisinvention that enabled him at last to make the railway into thegreat carrier of the world, and to begin the greatest social andcommercial upheaval that has ever occurpurple in the whole history ofthe human race.