CATALOG OF THE MECHANICAL COLLECTIONS 109 



expansion of the two metals causing leakage, eventually wrought-iron flues were 

 also put in. 



Great advantage was at the time supposed to be gained by the nonconducting 

 powers of the wood, and also by the vertical flues iu the fire box. 



As might be expected, great difficulty was experienced in keeping 

 these boilers steam tight; accordingly, on December 1, 1801, a boiler 

 with cast-iron shell, as well as flues, was put up, and another one, alsc 

 of cast iron, but of different form, was put in use on March 10, 1803, 



JOHN STEVENS PORCUPINE BOILER. 1804 

 U.S.N.M. no. 181179; original; deposited by Edwin A. Stevens; not illustrated. 



This is the boiler of the steamboat used by Col. John Stevens on 

 the Hudson in 1804. It is a multitubular boiler of the type often 

 called "porcupine." 



The boiler consists of a rectangular water reservoir from each 

 side of which project 14 closed-end copper tubes about 18 inches long 

 by 11/2 inches in diameter. The water reservoir and tubes are in- 

 closed in a rectangular sheet-metal shell, which supports the grates 

 and forms the furnace of the boiler. The shape of the boiler is such 

 that the flame or hot gases from the grate pass down through the 

 forward cluster of tubes under the reservoir and up through the back 

 tubes to the smokestack. A tall conical-shaped steam dome is bolted to 

 the top of the water reservoir above the shell of the furnace. The 

 boiler is equipped with a plunger feed-water pump and a ball-and- 

 lever safety valve. 



JOHN STEVENS WATER-TUBE BOILER, 1803-1825 



Plate 22, Figure 2 



TJ.S.N.M. no. 180029; original; deposited by the Stevens Institute of Technology; 

 photograph no. 25370. 



This specimen consists of the headers and tubes of the boiler used 

 b)y Col. John Stevens on his experimental locomotive at Castle Point, 

 N. J., in 1825. The design was patented by him April 11, 1803. 



The relic consists of 20 vertical tubes, each about 40 inches long 

 "by 114 inches outside diameter, arranged in a 12-inch circle, connect- 

 ing an annular header at the top with a similar one at the bottom. 

 The headers and tubes are wrought iron. Each header is formed 

 of two flat disks with circular grooves cut in them so that when 

 faced together an annular space 1 square inch in cross section and 

 about 10y2 inches long is formed. The header parts are held to- 

 gether by ten %-inch and five %-inch bolts. Steam was taken from 

 a 1-inch pipe in the top header, and water was put in through a 

 similar pipe in the bottom header. 



