83

Steam Xuri^ation.

the steam being blown through the hole, wouldput out the firei Besides giving the signal ofwhat was wanted, it would at once put an end tothe cause of danger.—Considered that the mer-curial gauge acted as a safety-valve, which couldnot be stopped or put out of order; and it had *the advantage of exhibiting, during all times ofthe boiler’s working, the state of the steam withinthe boiler, by the fluctuation that took place inthat column, as indicated by the appearance uponthe surface of the mercury. If the mercury be-came stationary, it might readily be suspectedthat that tube was stopped; therefore it wouldpoint out itself instantly that it had become notwhat it ought to be. The safety-valve had notthat advantage, as it did not indicate any thingtill the steam was blown out by raising the weight.

—With respect to the value of high-pressuresteam for working engines in Cornwall , of late aa most valuable improvement had taken place;and if it was an object to save coal to steam-vesselsupon a large scale, high-pressure steam becamean object of great importance to them, if appliedupon the principle that Mr. Wolfe had in the first -place introduced, but which had been applied byMr. Simms and others. Was of opinion that thosehigh-pressure boilers might be made with equalsafety as low-pressure boilers.—Had prepared astatement of the work done by the engines on theprincipal mines in the county of Cornwall . Itstated the consumption of coal and the work

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