adhesive weight
of the wheel upon the rail is greater than the weight to be dragged after
it." As to accidents, Stephenson said he knew of none that had occurred
with his engines. There had been one, he was told, at the Middleton
Colliery, near Leeds, with a Blenkinsop engine. The driver had been in
liquor, and put a considerable load on the safety-valve, so that upon
going forward the engine blew up and the man was killed. But he added,
if proper precautions had been used with that boiler, the accident could
not have happened. The following cross-examination occurred in reference
to the question of speed:--

"Of course," he was asked, "when a body is moving upon a road, the
greater the velocity the greater the momentum that is generated?"
"Certainly."--"What would be the momentum of 40 tons moving at the rate
of 12 miles an hour?" "It would be very great."--"Have you seen a
railroad that would stand that?" "Yes."--"Where?" "Any railroad that
would bear going 4 miles an hour: I mean to say, that if it would bear
the weight at 4 miles an hour, it would bear it at 12."--"Taking it at 4
miles an hour, do you mean to say that it would not require a stronger
railway to carry the same weight 12 miles an hour?" "I will give an
answer to that. I dare say every person has been over ice when skating,
or seen persons go over, and they know that it would bear them better at
a greater velocity than it would if they went slower; when they go quick,
the weight in a measure ceases."--"Is not that upon the hypothesis that
the railroad is perfect?" "It is; and I mean to make it perfect."

It is not necessary to state that to have passed the ordeal of so severe
a cross-examination scatheless, needed no small amount of courage,
intelligence, and ready shrewdness on the part of the witness. Nicholas
Wood, who was present on the occasion, has since stated that the point on
which Stephenson was hardest pressed was that of speed. "I believe," he
says, "that it would have lost the Company their bill if he had gone
beyond 8 or 9 miles an hour. If he had stated his intention of going 12
or 15 miles an hour, not a single person would have believed it to be
practicable."

The Committee also seem to have entertained considerable alarm as to the
high rate of speed which had been spoken of, and proceeded to examine the
witness further on the subject. They supposed the case of the engine
being upset when going at 9 miles an hour, and