Page:Report from the Select Committee on Steam Carriages.pdf/62



Mr. G. Gurney. 5 August, 1831. quantity of water in the boiler is the common glass guage, well known to those, acquainted with the subject.

Have you any guage to examine the intensity of the steam?—Yes, we have a piston which is forced oat in proportion to the pressure; in addition to the glass guages there are also stop cocks, so as to ascertain, by turning them, the actual height of water. I beg to state, that the safety plug has never, but four or five times, given way in all my experiments, and that has been in cases where we have been accidentally out of water in our tanks; no personal mischief can arise from such an accident. I am satisfied, without this plug an explosion would have taken place in some of the tubes. In large boilers, under those circumstances, inevitable destruction would have attended it.

Are you aware of the size of the cylinders and stroke of the Engines on the Manchester and Liverpool rail-road?—I believe them to be ten inches diameter, and about fourteen inches stroke. In some of the later Engines I believe they have been made of fourteen inches diameter, the stroke being the same; but I rather think that that size has been given up, and that they have returned again to the ten inches diameter.

What is the greatest weight, in proportion to its own weight, which any Carriage draws on a rail-road?—A Carriage was originally supposed to draw only three times its own weight on a rail-road; but in some experiments which I made in Wales with Mr. Crawshay, of Cwrfaithfa Castle, we found, in an experiment, that a Carriage draws thirty times its own weight. He has the minutes which we made upon the occasion; but I believe, in practice, they scarcely exceed five times, or from five to ten.

You have stated that in your Carriages you do not anticipate drawing more than the weight of the Engine?—Practically, on the common road, weight for weight. I explained in my former Evidence, that it was possible to do more under favourable circumstances; but circumstances vary so much on the