CHAP. XI. EXAMINED AS TO SPEED. 205 



adhesive weight of the wheel upon the rail is greater 

 than the weight to be dragged after it." There was a 

 good deal of interruption to the witness's answers by 

 Mr. Alderson, to which Mr. Joy more than once 

 objected. As to accidents, Mr. Stephenson 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 pre- 

 cautions had been used with that boiler, the accident 

 could not have happened. The following cross-exami- 

 nation 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 forty tons moving at the 

 rate of twelve 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 four miles an hour : I mean to say, 

 that if it would bear the weight at four miles an hour, 

 it would bear it at twelve." " Taking it at four miles 

 an hour, do you mean to say that it would not require a 

 stronger railway to carry the same weight twelve 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 such 

 an ordeal scatheless, needed no small amount of courage, 

 intelligence, and ready shrewdness on the part of the 



