simple and direct communication
between the cylinders and the wheels rolling upon the rails; joint
adhesion of all the wheels, attained by the use of horizontal
connecting-rods; and finally, a beautiful method of exciting the
combustion of the fuel by employing the waste steam, which had formerly
been allowed to escape uselessly into the air. Although many
improvements in detail were afterwards introduced in the locomotive by
George Stephenson himself, as well as by his equally distinguished son,
it is perhaps not too much to say that this engine, as a mechanical
contrivance, contained the germ of all that has since been effected. It
may in fact be regarded as the type of the present locomotive engine.

CHAPTER VI.
INVENTION OF THE "GEORDY" SAFETY-LAMP.

Explosions of fire-damp were unusually frequent in the coal mines of
Northumberland and Durham about the time when George Stephenson was
engaged in the construction of his first locomotives. These explosions
were often attended with fearful loss of life and dreadful suffering to
the workpeople. Killingworth Colliery was not free from such deplorable
calamities; and during the time that Stephenson was employed as a
brakesman at the West Moor, several "blasts" took place in the pit, by
which many workmen were scorched and killed, and the owners of the
colliery sustained heavy losses. One of the most serious of these
accidents occurred in 1806, not long after he had been appointed
brakesman, by which 10 persons were killed. Stephenson was working at
the mouth of the pit at the time, and the circumstances connected with
the accident made a deep impression on his mind.

Another explosion took place in the same pit in 1809, by which 12 persons
lost their lives. The blast did not reach the shaft as in the former
case; the unfortunate persons in the pit having been suffocated by the
after-damp. More calamitous still were the explosions which took place
in the neighbouring collieries; one of the worst being that of 1812, in
the Felling Pit, near Gateshead, by which no fewer than 90 men and boys
were suffocated or burnt to death. And a similar accident occurred in
the same pit in the year following, by which 22 persons perished.

It was natural that George Stephenson should devote his attention to the
causes of these deplorable accidents, and to the means by which they
might if possible be prevented. His daily occupation led him to think
much and deeply on t