The bronze bass-relief upon the monument, made from the working
drawing furnished by Mr. Dripps, is an exact representation of the
locomotive when it arrived in America.
The engine originally weighed about ten tons. The boiler was thirteen
feet long and three feet six inches in diameter. The cylinders were
nine inches by twenty inches. There were four driving wheels, four
feet six inches in diameter, arranged with outside cranks for
connecting parallel rods, but owing to the sharp curves on the road
these rods were never used. The driving wheels were made with cast
iron hubs and wooden (locust) spokes and felloes. The tires were of
wrought iron, three quarters of an inch thick, the tread being five
inches and the depth of flange one and a half inches. The gauge was
originally five feet from center to center of rails. The boiler was
composed of sixty-two flues seven feet six inches long, two inches in
diameter; the furnace was three feet seven inches long and three feet
two inches high, for burning wood. The steam ports were one and
one-eighth inches by six and a half inches; the exhaust ports one and
one-eighth by six and a half inches; grate surface, ten feet eight
inches; fire box surface, thirty-six feet; flue surface, two hundred
and thirteen feet; weight, without fuel or water, twenty-two thousand
four hundred and twenty-five pounds.
After the valves were in gear and the engine in motion, two levers on
the engineman's side moved back and forth continuously. When it was
necessary to put the locomotive on the turntable, enginemen who were
skilled in the handling of the engines first put the valves out of
gear by turning the handle down, and then worked the levers by hand,
thus moving the valves to the proper position and stopping the engine
at the exact point desired.
The reversing gear was a very complicated affair. The two eccentrics
were secured to a sleeve or barrel, which fitted loosely on the crank
shaft, between the two cranks, so as to turn freely. A treadle was
used to change the position of this loose eccentric sleeve on the
shaft of the driving wheel (moving it to the right or left) when it
was necessary to reverse. Two carriers were secured firmly to the body
of this shaft (one on each side of the eccentrics); one carrier worked
the engine ahead, the other back. The small handle on the right side
of the boiler was used to lift the eccentric rod (which passed forward
to the rock shaft on the forward part of the engine) off the pin, and
thus put the valves out of gear before it was possible to shift the
sleeve and reverse the engine.
Great similarity will be noticed in the American locomotives built for
many years after the arrival of the "John Bull," especially in the
matter of making the keys, brasses, etc., on the connecting rods, and
in the construction of valves, fire box and tubes. Even the old plan
of setting the ends of the exhaust nozzle high up in the smoke box,
which was discontinued when the petticoat pipe came in use, is now
again resorted to in connection with the extended smoke box of modern
locomotives.