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Show creases. Other means of arriving at a similar result are admission of air through positively controlled valves interconnected with the usual butterfly butter-fly throttle, or by devices that reduce the orifice of the atomizing nozzle. In many carbureters made for automobile auto-mobile uses the floats and float chambers cham-bers are made concentric In form, surrounding sur-rounding the atomizing nozzle, the purpose being to maintain the level of fuel in the nozzle, regardless of fore-and-aft or lateral tilting of the ve-hicla. ve-hicla. In a flying machine this seems hardly hard-ly necessary, because longitudinal tilting never under normal conditions can exceed the comparatively flat angles an-gles of gliding or ascending, while lateral tilting Is compensated for by the centrifugal force set up In turning, which acts upon the liquid within the float chamber as well as upon other elements el-ements in the machine. Many of the foremost designers favor positive fuel Injection Into ythe cylinders in place of carbureters. Tills pt-jitlve form admits of much closer regulation than is possible with the c.?j.bureter. Because the injection may ba timed, it permits of high compressions compres-sions without preignltlon, the fuel Injection In-jection being delayed until the ignition igni-tion is wanted. Obviously one of the chief objections objec-tions to the general employment of fuel injection is that of commutating the fuel to the different cylinders without the objectionable scheme of employing a plurality of pumps, one for each cylinder. This, besides adding add-ing complication, scarcely will admit of such adjustment as to give exactly uniform results in all of the cylinders difficulty which Is no greater than that of equalizing the lntako manifold from a carbureter so as to produce uniform feeding. (Couyrlitlit, 1911, by W. a. Chapman.) When the time comes that an aviator avia-tor may make adjustments of his carbureter car-bureter as well as other portions of the motor upon which he -depends even more than does the chauffeur on lis automobile engine, the problem of carburet Ion w ill not present so many difficult views. The ordinary carbureter, say.-, Victor Ioughr.ed, author and engineer, Is in most respects a nonpositivo mechanism. mecha-nism. In consequence of which its functioning func-tioning Is attended with many uncertainties. uncer-tainties. This Is obviously true even in the automobile field. Increase the motor car difficulties aiany fold and add the care that the aviator has to exercise in operating Js Tying I'.achlne and you may re- alize what carburetion In air-machine motors means. Yet the carbureters in flying machines ma-chines are very similar to those in the best automobile engines. To secure se-cure uniformly proportioned fuel, It is necessary that the fuel level In the atomizing nozzle be maintained fairly fair-ly constant. Also for variable speed engines, it is desirable that the carbureter car-bureter action be such as not to derange de-range the mixture materially through the suction from different speeds. With no moans of compensation, at higher engine speeds and consequent higher suction extra air is admitted Ihrough a valve automatically operated, oper-ated, opening wider as the suction in- |