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TRANSACTIONS OF THE 



I am inclined to believe that nearly all the explosions of boilers 

 that so frequently occur, may be attributed to the use of bad iron 

 for boiler plates; therefore, it is incumbent upon boiler makers 

 to purchase their plates from those manufacturers only, who have 

 established their credit as beinf? well informed judges of the quality 

 of iron. Only those who prepare the sheets can know, and they 

 cannot always be relied on, for an iron will sometimes resist 

 shearing, punching, forging and riveting, remarkably well, and 

 still be entirely unsuitable for a boiler. To know iron well, the 

 manufjicturer must have his eye upon it from the ore to the forge. 

 The best boiler iron is manufactured from ores obtained from the 

 Missouri iron mountain, parts of New-Jersey and Eastern Penn- 

 sylvania. But even they are often destroyed on the furnace by 

 hot blast, which will not resist heat, and is, therefore, not suita- 

 ble, though it may be fibrous, and even tenacious in the sheet, 

 but it always becomes exceedingly brittle when much heated, and 

 then cooled suddenly. The test for proving iron, is to make it 

 red hot, and thrust it into cold water; if, after this treatment, it 

 remains tenacious, it is good, if not, it is unfit for the plates of 

 boilers, and should on no account be used. 



I would not .place confidence in any wrought iron; the fibres 

 and tenacity of which are not retained after being subjected to in- 

 tense heat, and then suddenly cooled. 



If boiler manufacturers would only govern themselves by this 

 simple rule, sorrow and misfL)rtune would not be so often carried 

 into thousands of happy homes, by the sacrifice of lives caused 

 by the explosion of boilers. 



If the iron is of good quality, and the plates thoroughly riv- 

 etted with larger rivets than are generally used, the safety valve, 

 reliable, the boiler not overtasked, and tlie water invariably kept 

 a few inches above the flue, and the steam and water always kept 

 in constant motion, under the superintendance of a careful fire- 

 man and judicious engineer, accidents would rarely occur. 



Many suppose that high pressure alone is the cause of explo- 

 sion ; this cannot be ; for a cylindrical boiler, made of quarter 

 inch iron, is in every case sufficiently strong to resist any press- 

 ure usually practiced. I have known boilers to explode by a 

 pressure very far below the strength of quarter-inch plates, by 

 suddenly generating a large quantity of steam. A higli tension 

 of steam cannot explode a boiler, unless it is driven beyond' the 

 strength of the iron. You may alwaj'S feel safe if tlie steam is 

 permitted to escape gradually. A very large load of gunpowder 



