The Vaporizing Of Paraffin for High-Speed Motors
(Electric Ignition Type)

PETROL CARBURETTORS. 25 purpose, being alike exposed to jolting and to quick clianges in temperature, all forms of surface carburettors proved fickle and at times extremely variable in action, and at their best required skilful manipulation from time to time to compensate for differences in fuel density. With the practice of employing electric ignition and throttle control. carburettors were at first used in which. it was necessary to regulate either the fuel or air supply, or both, by hånd, thus necessitating incessant attention, and, with all, uncertain results, as no two drivers would be in complete agreement as to the best procedure under the ever-changing running conditions imposed by varying car construction, road surfaces, and other factors. How- ever, soon after the practice of fitting carburettors with some compensating device for varying load and speed conditions, the running of auto-motors became not only much steadier, but much less troublesome; the carburet- tors principally in vogue folio wing this impro vement took the form of that shown in Figs. 17 and 18 for several years. Immediately following this, the De Dion central feed (Fig. 19) carburettor was introduced, then the Longuemare (Fig. 22) with an equivalent action obtained by a pulsating combined air valve and choke-tube, d, a method lat er adopted in the Rover carburettor. But, with the demand for a greater range of speed control, it was found that the addition of a supplementary air valve was inadequate in the manner then applied— i.e., as fitted with a comparatively short helical spring that imposes an incréäsing resistance to opening; conse- quently, attention was directed towards some method for obtaining a more equable regulation by automatic means, and, as a result of this, there first appeared the Krebs