722 Transactions of the American Institute. 



these bolts been secured by nuts on the outside of the plates, the box 

 would have borne an enormously greater pressure than that which 

 exploded it. Between the bolts there was a small permanent stretch- 

 ing of the plates, giving each space between the bolts a slightly dishing 

 or bulged form, in addition to the general bulging of the plates, thus 

 forming a system of secondary bulges, as it were; and abound every 

 bolt both plates were strongly marked by a congeries of circular cris- 

 pations. 



The conclusions from this experiment are, that a gradually accu- 

 mulating steam pressure in a boiler can produce a true explosion, 

 violently hurling its fragments, with a loud report, to a considerable 

 distance, even though eighty-four per centum of its capacity be filled 

 with water ; and that screw bolts should not be used in boiler con- 

 struction without nuts, or having, as an equivalent, a large portion of 

 their ends formed into massive rivet-heads ; because the stretch of the 

 plates is sufficiently great, under a much less pressure than will frac- 

 ture the bolts or strip the threads, to allow the latter to slip through 

 uninjured. 



Previous to this experiment the box had been subjected, at Sandy 

 Hook, to a hydrostatic pressure of 138 pounds per square inch, and to 

 a steam pressure of 102 pounds per square inch, without fracture. 



Experiment on the 23d of November, 1871. 



On the twenty-third ultimo a last experiment was made, by 

 exploding a boiler in the presence of the undersigned and the follow- 

 ing gentlemen, namely : Captain W. W. Woolsey, superintendent of 

 the Jersey City ferry ; William and Andrew Fletcher, of the firm of 

 Fletcher, Harrison & Co., engine and boiler makers; Anning Smith, 

 superintendent of the North-Shore Ferry Company ; J. B. Collin, 

 mechanical engineer of the Pennsylvania Central railroad ; William 

 A. Dripps ; Thomas Lingle, of the Camden and Amboy railroad ; 

 Wm. Brown, of the Camden and Amboy railroad. 



The boiler that was exploded during this experiment was built by 

 T. F. Secor in 1 845, and taken out of the steamboat Bordentown in 

 August last, after having been twenty-five years in use. When taken 

 out the inspector's certificate allowed it to be worked with a pressure 

 of thirty pounds to the square ineh. It was a horizontal fire-tube 

 boiler, with the tubes returned immediately above the furnace and 

 combustion chamber. 



It had but one furnace, and that was eleven feet five inches in 

 width, with grate bars seven feet in length. The top of the furnace 



