The atomizer acts on the same principle as the medical or perfumery atomizer, the high pressure jet playing directly across the open end of the oil passage as shown by Fig. A. As the vacuum created by the blast is very low, and has little effect in lifting the fuel to the burner, the oil either is made to flow by gravity or by a pump. In the figure the oil in the upper passage is shown pouring down in front of the air or steam jet issuing from the lower port. Both ports are supplied by the pipes shown by the circular openings at the right. The steam and oil are controlled by independent valves placed in the two passages. In practice the oil and steam openings at the end of the burner may be either single or multiple round openings or long thin slots, the former style being the most common. Since only a small amount of air is admitted through the blast nozzle, far too little to completely consume the oil, the air for the combustion is admitted through openings in the combustion chamber proper, this air being supplied by natural draft or by blower. In some cases the burner is entered into the furnace through an opening that is much larger than the burner itself. The atmospheric air enters through baffle plates in this opening which impart a whirling motion to the air that passes over the burner. This is of considerable aid in maintaining complete combustion in the furnace, and also tends to prevent deposits in the burner. [Illustration: Fig. 135. Showing the Different Classes of Oil Burners. ] [Illustration: Fig. F. Mixed Pressure Burner, Using Both Steam and Low Pressure Air. ] [Illustration: Fig. G. Burner Used by the Pennsylvania Railroad Under Locomotives. ] In the injector type of burner shown by Fig. B the air or steam nozzle terminates inside of a shell and is completely surrounded by the oil. A mixture of air and oil issues from main nozzle shown by (2). When the air or steam blows through the inner opening, a partial vacuum is formed in the space (1) which draws the oil into the burner from the supply pipe. On entering this vacuous space the oil comes into contact with the jet and is blown out through the opening (2) in the form of a spray. This vacuum is high enough to lift the fuel for a considerable distance without the aid of a pump and for this reason is the type most commonly met with in practice. A boiler or furnace equipped with this burner will lift the oil directly to the furnace from the reservoir in the same way that a feed water injector will lift water into the boiler. With the commercial injector, the position of the steam jet is made adjustable in relation to the main jet to meet different feed conditions. The steam enters the inner port through the end of the pipe shown at the right. The oil enters the outer port at the right through a port not shown. [Illustration: Fig. H. Lassoe-Lovelsin Burner. ]