Page:Report from the Select Committee on Steam Carriages.pdf/44



Mr. G. Garney. 3 August, 1831. them?—To about 800 lbs.; I think they would bear 2,000 lbs.

What is the greatest pressure they would bear?—It is impossible to say. I have never been able to hurst one when well made, when lapped and welded. What is the average pressure on the boiler per square inch, in your ordinary rate of travelling? About 70 lbs.

And you have tried the tubes to 800?—Yes, we sometimes may work up to 100lbs, and 120lbs.; but that is a case of great emergency.

What is the greatest probable pressure it will be exposed to?—Never more than 130 lbs.; the safety valve blows at 70 lbs, to the inch; it is generally on the lift on a level hard road; I do not think that the pressure is more than 20 lbs, to an inch on the piston. Is it likely that persons would ordinarily work with the safety valve on the lift?-Yes; or nearly so, sometimes.

Is there not a waste of fuel when you work on the lift?—It will be in proportion to the escape of steam from the safety-valve; the pressure on the boiler is 70 lbs.; on the Engine frequently it does not exceed 20 lbs, to an inch; and when I was asked the pressure I worked at. I supposed the question referred to the pressure on the piston collectively.

What is the thickness of your tubes?—The thickness of the iron is about the eighth of an inch.

What is the thickness of your working cylinder?—It is about three quarters of an inch; it has also ribs round it.

Of what metal is your working cylinder formed?—Cast-iron; we have worked gun metal, but cast-iron appears to be best.

Have you found that there is great facility in guiding those Carriages?—I have always found the most perfect command in guiding them.

Supposing you were going at your ordinary rate of eight miles an hour, could you stop immediately, or would the carriage run for any distance?—In case of emergency, we might instantly throw the steam on the reverse side of the pistons, and stop within a few