the absence of springs.

[Picture: The Spur-gear]

The wheels of the locomotive were all smooth, Mr. Stephenson having
satisfied himself by experiment that the adhesion between the wheels of a
loaded engine and the rail would be sufficient for the purpose of
traction. Robert Stephenson informed us that his father caused a number
of workmen to mount upon the wheels of a waggon moderately loaded, and
throw their entire weight upon the spokes on one side, when he found that
the waggon could thus be easily propelled forward without the wheels
slipping. This, together with other experiments, satisfied him of the
expediency of adopting smooth wheels on his engine, and it was so
finished accordingly.

The engine was, after much labour and anxiety, and frequent alterations
of parts, at length brought to completion, having been about ten months
in hand. It was placed upon the Killingworth Railway on the 25th July,
1814; and its powers were tried on the same day. On an ascending
gradient of 1 in 450, the engine succeeded in drawing after it eight
loaded carriages of thirty tons' weight at about four miles an hour; and
for some time after it continued regularly at work.

Although a considerable advance upon previous locomotives, "Blutcher" (as
the engine was popularly called) was nevertheless a somewhat cumbrous and
clumsy machine. The parts were huddled together. The boiler constituted
the principal feature; and being the foundation of the other parts, it
was made to do duty not only as a generator of steam, but also as a basis
for the fixings of the machinery and for the bearings of the wheels and
axles. The want of springs was seriously felt; and the progress of the
engine was a succession of jolts, causing considerable derangement to the
machinery. The mode of communicating the motive power to the wheels by
means of the spur-gear also caused frequent jerks, each cylinder
alternately propelling or becoming propelled by the other, as the
pressure of the one upon the wheels became greater or less than the
pressure of the other; and when the teeth of the cogwheels became at all
worn, a rattling noise was produced during the travelling of the engine.

As the principal test of the success of the locomotive was its economy as
compared with horse power, careful calculations were made with the view
of ascertaining this important point. The result was, that it was found
the working of the engine was