1. The engine must effectually consume its own smoke.
2. The engine, if of six tons weight, must be able to draw after it, day by day, twenty tons weight (including the tender and water-tank) at ten miles an hour, with a pressure of steam on the boiler not exceeding fifty pounds to the square inch.
3. The boiler must have two safety-valves, neither of which must be fastened down, and one of them be completely out of the control of the engineman.
4. The engine and boiler must be supported on springs, and rest on six wheels, the height of the whole not exceeding fifteen feet to the top of the chimney.
5. The engine, with water, must not weigh more than six tons; but an engine of less weight would be preferred on its drawing a proportionate load behind it; if only four and a half tons, then it might be put on only four wheels. The Company to be at liberty to test the boiler, etc., by a pressure of one hundred and fifty pounds to the square inch.
6. A mercurial gauge must be affixed to the machine, showing the steam pressure above forty-five pounds per square inch.
7. The engine must be delivered, complete and ready for trial, at the Liverpool end of the railway, not later than the 1st of October, 1829.
8. The price of the engine must not exceed £550.
[214] The inventor of this engine was a Swede, who afterwards proceeded to the United States, and there achieved considerable distinction as an engineer. His Caloric Engine has so far proved a failure, but his iron cupola vessel, the “Monitor,” must be admitted to have been a remarkable success in its way.
[219] The “Rocket” is now to be seen at the Museum of Patents at Kensington, where it is carefully preserved.