Igg BULLETIN 173, U. S. NATIONAL MUSEUM 



proper strength at all speeds. A modern carburetor using this prin- 

 ciple is the Zenith described below. The Tillotson carburetors 

 (below) show the use of the bypass, accelerating pump, and econo- 

 mizer in modern automobile carburetors. 



DURYEA CARBURETOR 

 Plate 34, Figure 1 



U.S.N.M. no. 307199; original, gift of Inglis M. Uppercu ; photograph no. 18076. 



This carburetor was made by Charles E. Duryea and was used by 

 him on his successful gasoline automobile of 1892-93. It is a posi- 

 tively controlled, constant-level, induced-jet, spray carburetor, in 

 which the quantity of gasoline supplied to the jet is controlled by a 

 needle valve and the volume of air is determined by the setting of 

 a rotary-disk valve. 



The carburetor consists of two tubular chambers put together in 

 the form of a T, with the axes of both chambers horizontal. The 

 construction is evident from the illustration. The short chamber 

 through which gasoline is permitted to flow corresponds to the float 

 chamber of the present-day carburetor. Entering it are two pipes, 

 one of which leads to a tank above the carburetor, the other to a 

 tank below it. Gasoline flowed continuously into the chamber from 

 the tank above and overflovv-ed from the chamber to the tank below, 

 maintaining a constant level of gasoline somewhere between the lip 

 of the overflow pipe and its center. The rate of flow was controlled 

 by a valve and could be observed through a sight glass in the feed 

 line. The gasoline that reached the lower tank was returned to 

 the upper one by means of a hand pump. The gasoline entered the 

 small space about the shaft of the needle through the valve seat 

 and stood in this space at the height of the gasoline in the constant 

 level chamber. The jet consists of this space and a horizonal tube 

 of very small bore leading from it slightly above the level of gasoline 

 to the mixing chamber. The mixing chamber is simply a hollow 

 tube obstructed by a diaphragm having a large circular hole through 

 its center and small openings near the wall of the tube. Against 

 the diaphragm is a movable disk similarly pierced and carrying 

 at its center a tube, which is slightly converging in the direction of 

 flow and into the entering end of which is bent the small-bore jet 

 tube. At all times the opening through the center of the flow tube 

 and diaphragm is unobstructed, but the openings in the diaphragm 

 near the wall of the tube may be varied or closed by moving the disk. 

 Air is drawn through the mixing chamber by the suction of the intake 

 stroke of the piston of the engine, and that part of the air passing 

 through the tube draws a spray of gasoline from the jet tube. This 

 gasoline mixes with the air and passes to the engine. Both the needle 



