mes of a more promising character, abandoning the engine
to other mechanical inventors, though little improvement was made in it
for several years. An imaginary difficulty seems to have tended, amongst
other obstacles, to prevent its adoption; viz., the idea that, if a heavy
weight were placed behind the engine, the "grip" or "bite" of its smooth
wheels upon the equally smooth iron rail, must necessarily be so slight
that they would whirl round upon it, and, consequently, that the machine
would not make progress. Hence Trevithick, in his patent, provided that
the periphery of the driving-wheels should be made rough by the
projection of bolts or cross-grooves, so that the adhesion of the wheels
to the road might be secured.

Following up the presumed necessity for a more effectual adhesion between
the wheels and the rails, Mr. Blenkinsop of Leeds, in 1811, took out a
patent for a racked or tooth-rail laid along one side of the road, into
which the toothed-wheel of his locomotive worked as pinions work into a
rack. The boiler of his engine was supported by a carriage with four
wheels without teeth, and rested immediately upon the axles. These
wheels were entirely independent of the working parts of the engine, and
therefore merely supported its weight upon the rails, the progress being
effected by means of the cogged-wheel working into the cogged-rail. The
engine had two cylinders, instead of one as in Trevithick's engine. The
invention of the double cylinder was due to Matthew Murray, of Leeds, one
of the best mechanical engineers of his time; Mr. Blenkinsop, who was not
a mechanic, having consulted him as to all the practical arrangements.
The connecting-rods gave the motion to two pinions by cranks at right
angles to each other; these pinions communicating the motion to the wheel
which worked into the cogged-rail.

Mr. Blenkinsop's engines began running on the railway from the Middleton
Collieries to Leeds, about 3.5 miles, on the 12th of August, 1812. They
continued for many years to be one of the principal curiosities of the
place, and were visited by strangers from all parts. In 1816, the Grand
Duke Nicholas (afterwards Emperor) of Russia observed the working of
Blenkinsop's locomotive with curious interest and admiration. An engine
dragged as many as thirty coal-waggons at a speed of about 3.25 miles per
hour. These engines continued for many years to be thus employed in the
haulage of coal, and furnished