Experiments upon the Advantage of Throttling Steam. 389 Trials F and G were upon condemned pipes. ~' broke with a weigh~ of 8400 ]bs., and was very defective at the point of rupture, o broke with a weight of 8325 lbs.; the casting was of poor iron and east with wet core, having caused a boiling surface. The tensile strength of a pipe 30 inches in diameter, cast at the Florence Foundry, ~. J., and afterwards broken up, was tried at the proving machine of the West Point Foundry, and it was found

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... qual to 22,133 lbs. per square inch. This might be considered an average specimen of the iron used in the American foundries for pipe castings. Specimens taken from pipes cast at the Phoenix Iron Works, Glasgow, Scotland, were sent to tim South Boston Foundry, Messrs. Alger & Co., and tried by their proving machine with the following results :