7(j(j Transactions of the American Institute. 



pressure of the steam in another boiler ; also, to observe the effect 

 of raising the safety valve suddenly, and to pursue the experiments 

 upon various points, just as far as the funds contributed will enable 

 the experiments to be made. I will here present a paper prepared 

 by me for the Journal of the Franklin Institute. 



EXPEKIMENTAL StEAM BoiLEK EXPLOSIONS. 

 [Discussion of the third experiment at Sandy Hook, New York.] 



By Prof. R. H. Thurston. 



The violence with which the third boiler, experimented upon at 

 Sandy Hook, exploded has raised a doubt in the minds of many 

 engineers whether some extraordinary and unfamiliar cause may not 

 "have operated in the production of such astonishing effects. No 

 positive proof of the non-existence of such causes can be given, but 

 the following considerations will at least indicate that we may find, 

 in well understood and certainly existing causes, ample power to pro- 

 duce all of the effects noted. 



The steam boiler referred to weighed 40,000 pounds, and contained 

 about 30,000 pounds of water and 150 pounds of steam, all of which 

 had a temperature of 301° Fahr., when, at the moment before explo- 

 sion, the steam pressure was fifty-three and one-half pounds above 

 that of the atmosphere. 



When the explosion took place, the whole mass at once liberated 

 its heat, until it had cooled down to the temperature of vapor under 

 the pressure of the atmosphere. 



In this act the water gave off 30,000 x 89° = 2,670,000 British ther- 

 mal units, and the steam lost the difference between its total heat at 

 301° and that of 212° Fahr., or 150 x27.2°=4,080 thermal units. 

 The sum 2,670,000 + 4,080 =2,674,080^ thermal units has an equiva- 

 lent in mechanical energy of 2,674,0*80x772=2,064,389,760 foot- 

 pounds, arid this was sufficient to have raised the whole boiler and 

 contents, weighing 70,000 pounds, to a height of 29,491.282 feet — 

 more than five miles. This represents the maximum possible effect. 



The least effect would have been produced had the liberation of 

 heat and the production of additional quantities of steam, within the 

 mass of water and at its surface, been so sluggish as to have given no 

 assistance in propelling the fragments of the ruptured boiler — the 

 whole destructive work being done by the simple expansion of the 

 steam which filled the steam spaces. 



The total amount of mechanical energy set free from the steam 

 alone was 4,080x772=3,149,760 foot-pounds, or sufficient to raise 



