1 ] (5 Steam Navigation.

three of the largest mines in Cornwall , the unitedmines of Crowan, Dolcoath, and Weal Unity,they wished to state their hope, that the Legis­ lature would not interfere to prevent the use ofhigh-pressure engines, either on board boats, orin any other \fay.

Mr. Thomas Lean, Inspector of Steam engines, ofCrowan, in Cornwall , called in and examined.

Was employed by nearly the whole of theminers in Cornwall to inspect their engines, andmake monthly reports of the work they performed.—Conceived there was no danger whatever in theuse of high-pressure steam engines; and for thisreason, that, in general, for an engine intended tobe worked with high steam, the materials weremade stronger in proportion than the materialsused for steam of low-pressure.—Considered it ofimportance that every boiler should have twosafety-valves, one of which should be confinedfrom the engine-man.—In a boiler in which greatstrength was required, would certainly recom-mend cast iron, and had no doubt but it could bemade much stronger than w'rought iron, the ex-plosions that had happened in Cornwall having allbeen in w r rought-iron boilers, and from low-pres-sure steam.—In every boiler that was built, therewas one part of it weaker than another, and it washardly possible for a boiler to be thrown about infragments to do mischief. Should not feel anyhesitation to sit on the cast-iron boilers in Corn-