OF THE IRK, LOCOMOTIVE ENGINE. 527 
Mr. Charles Frederick Beyer, also said, that 
_he believed the copper must have been cracked. 
It is probable, not only that the top of the fire- 
box was cracked, but, that there was very little, 
or no water, upon it; and, that, therefore, it would 
be red-hot, when, from the peculiar nature of 
copper and brass, the copper plate would bend 
easily, and would also become very brittle. 
Mr. Alfred S. Tayler, Lecturer on chemistry, 
in Guy’s Hospital, says, in his letter to Mr. 
Chapman, that Engineers do not appear to be 
sufficiently aware, that the strength of copper is 
diminished by raising the temperature, in a much 
greater proportion than the strength of iron. The 
fact is, that Engineers do not make the copper 
plate of the fire-box, half thick enough. And, he 
adds, that, besides this, the square form of the 
fire-box is bad. 
