16 
They were all high pressure engines, and some portion of 
the variance might have arisen from leakages, &e. He 
did not think that the saving in the Cornish engine 
•was wholly to be attributed to the construction of the 
boiler. Upon the whole, he thought that the sugges- 
tion to adopt the Cornish boiler was a very valuable one, for 
it was equally adapted to high and low pressure engines, 
care being taken as to the relative strength of the internal 
and external surfaces. With respect to the cliimneys, he 
thought it probable that the widening of the mouth would 
have the effect of increasing the draft, but nothing could 
decide that so well as experiments, and he hoped they would 
soon be made. » 
Mr. Hartop was exceedingly obliged to Mr. Marshall for 
the remarks which he had made. He quite agreed 
with him in his observation as to staying the boilers, and 
perhaps he should have gone further into detail on that 
subject had he not been wishful to avoid unnecessarily 
occupying the time of the meeting, especially after the great 
deal of information which had been recently laid before the 
public by Mr. Armstrong of Manchester, who had written a 
really practical book on the subject. There was, however, 
one part of the subject to which Mr. Marshall had referred 
that he would direct the attention of the meeting to for a 
few moments. Mr. Marshall had observed that accidents 
happened to cylinder-shaped boilers on board steam packets ; 
that was, doubtless, true, and nothing could more conduce 
to the comfort of the travelling portion of the community 
than a successful endeavour to remedy an evil of that 
description. He had spent much time in considering the 
causes of the bursting of boilers on board steam packets, and 
a remedy for it, for that was the only place where any real 
risk was run. The fact had not occurred of any great 
injury having been done by the bursting of a boiler of a 
locomotive steam engine, which, next to that of a steam 
packet, was one with which the pubUc were most likely to 
come in contact. Any little device that would save even 
one accident of this description would be well worthy of 
ten minutes' consideration. He was very confident that it 
was not any peculiarity in the shape of the boilers on 
board packets that had been the cause of their burst- 
ing ; but he was inclined to think that it was frequently 
owing to in'egularity in the supply of cold water. The 
depth of water in the boiler, over the fireplace, was some- 
times not more than ten inches or a foot, and, therefore, 
if any interruption in the supply of water took place, the 
flue became red hot, which might occasion it to collapse, or a 
fresh supply of water might cause a blow up. As the depth 
of the water in the cylindrical boilers was so very 
small, it became the more important that the supply of water 
