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 That the inspector shall examine such safety-valves, and shall certify what is the pressure at which such safetyvalves shall open, which pressure shall not exceed onethird of that by which the boiler has been proved, nor one-sixth of that which by calculation...  An Historical and Descriptive Account of the Steam Engine: Comprising a ... - Էջ 98 Charles Frederick Partington - 1822 - 277 էջ Ամբողջությամբ դիտվող -
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