had been at first a mere clumsy mining contrivance, became developed
into a smooth and easy iron highway for the rapid and convenient
conveyance of goods and passengers over immense distances. Of course,
this great invention, like all other great inventions, was not the work
of one day or one man. Many previous heads had helped to prepare the way
for George Stephenson; and George Stephenson himself had been working at
the subject for many years before he even reached the first stage of
realized endeavour. As early as 1814 he constructed his first locomotive
at Killingworth colliery; it was not until 1822 that he laid the first
rail of his first large line, the Stockton and Darlington Railway.

Stephenson's earliest important improvement in the locomotive consisted
in his invention of what is called the steam-blast, by which the steam
is made to increase the draught of the fire, and so largely add to the
effectiveness of the engine. It was this invention that enabled him at
last to make the railway into the great carrier of the world, and to
begin the greatest social and commercial upheaval that has ever occurred
in the whole history of the human race.

Meanwhile, however, George was not entirely occupied with the
consideration of his growing engine. He had the clocks and watches to
mend; he had Robert's schooling to look after; and he had another
practical matter even nearer home than the locomotive on which to
exercise his inventive genius. One day, in 1814, the main gallery of the
colliery caught fire. Stephenson at once descended into the burning pit,
with a chosen band of volunteers, who displayed the usual heroic courage
of colliers in going to the rescue of their comrades; and, at the risk
of their lives, these brave men bricked up the burning portion, and so,
by excluding the air, put out the dangerous fire. Still, even so,
several of the workmen had been suffocated, and one of the pitmen asked