CATALOG OF THE MECHANICAL COLLECTIONS 87" 



through these tubes. Tlie steam enters the space between the tube 

 sheets at the top at one side, flows around the tubes, and down and out 

 (as condensate) the opposite side at the lower end into the air pump. 

 The steam and cooling water apparently travel in the same direction,, 

 that is, downward. 



The air pump consists of two vertical tubes joined at the bottom 

 to form a V-tube. One of the two tubes is bolted to the side of the 

 condenser so that the bottom of the tube is some distance below the 

 bottom of the condenser ; the condensate outlet of the condenser is at a 

 point about two-thirds of the height of the tube and opening into 

 it through a hinged valve (the inlet valve of the pump). The outlet 

 valve of the pump is in the top of the tube above the inlet valve. A. 

 piston is fitted to the other tube of the pump. The movement of 

 the piston in the one tube caused a water column to rise and fall in 

 the other tube, drawing in air and water from the condenser and 

 discharging it (the air first) from the top of the tube. 



The condenser has all the elements of the present-day surface con- 

 denser, which is the type in most general use, and the air pump 

 incorporates the principle upon which most present successful vac- 

 uum pumps operate. Watt did not, however, overcome the difficulties 

 of maintaining the tubes tight in the tube sheets, and he supplied the 

 jet type of condenser with his engines. (See the Fulton engine draw- 

 ings above.) 



STEVENS SURFACE CONDENSER, 1862 



U.S.N.M. no. 308665; original patent model; transferred from the United States 

 Pateat Office; not illustrated. 



This model was submitted with the application for the patent 

 issued to Francis B. Stevens, of New York, N. Y., October 28, 1862, 

 no. 36807. 



The model represents a surface condenser formed of coils of pipe 

 to be located outside of the hull of a vessel. The peculiar feature is 

 that cocks and valves are provided so that the condenser ca-n be dis- 

 connected from the engine and used to distil sea water for the boilers 

 and also permit steam to be blown through the condenser for clean- 

 ing the tubes. 



STEVENS STEAM-ENGINE CONDENSER, 1863 



U.S.N.M. no 30923S ; original patent model ; transferred from the United Statea 

 Patent Office; not illustrated. 



This model was submitted with the application for the patent issued 

 to Francis B. Stevens, November 3, 1863, no. 40510. 



The condenser represented in the model consists of a large vertical 

 cylinder and pump plunger with various connected chambers designed 



