CATALOG OF THE MECHANICAL COLLECTIONS HJ 



the other lower drums are located just above the grates. The upper 

 drums are connected to one large horizontal cross drum. The drums 

 are flattened for greater convenience in joining the two rows of ver- 

 tical tubes. Passages are provided in the brickwork through which 

 air for combustion is drawn and preheated. 



TROWBRIDGE STEAM GENERATOR, 1878 



U.S.N.M. no. 308699 ; original patent model ; transferred from the United State* 

 Patent Office ; not illustrated. 



This model was submitted with the application for the patent issued 

 to W. P. Trowbridge, of New Haven, Conn., January 1, 1878, no. 

 198863 ; Automatic Boiler & Engine Co., assignee. 



The model represents a small vertical coiled water-tube boiler pro- 

 vided with a stack or hopper in the center of the shell, which acts as 

 a fuel reservoir to supply fresh fuel to the fire automatically. 



The boiler consists of a cylindrical shell the base of which forms 

 the ashpit above which the grates are supported. The shell above the 

 grates is built with increasing diameter upward to form the firebox,. 

 and immediately above this it is contracted for a short distance and 

 then continues in a cylinder of constant diameter. Around the fire- 

 box and fitting closely to the shell is a single coil of tubing, which is 

 continued up through the cylindrical portion where alternate coils 

 are staggered slightly. Projecting downward within the coils is a 

 second cylindrical shell closed at the top by a removable cover. This 

 shell is used as a fuel reservoir and feeding device and also forms an 

 annular passage with the outer shell which requires the hot gases of 

 combustion to pass over the coils. The automatic fuel supply device 

 is not shown or described. 



NATIONAL WATER-TUBE BOILER, 1885 



PlATE 23 



U.S.N.M. no. 309374; model; gift of .John A. Manley ; photograph no. 2799D. 



This is a model of an inclined-tube solid-header boiler of the type 

 constructed by the National Water Tube Boiler Co. about 1885-1890. 

 It incorporates many features patented by W. E. Kelly. . 



The model represents an inclined-tube, 3-pass, inclined solid header 

 boiler, with longitudinal drum. The risers both front and back con- 

 sist of one group of four tubes arranged in a diamond-shaped group. 

 The boiler is complete with ornamental front, gauges, and blow-off 

 safety valve. It is equipped with grates for hand firing. The brick- 

 work setting is cut away to show the boiler parts and the method of 

 suspension. 



