Improvements relating to Sparking Plugs

27,937. Moonen, E., and Dumaire, A. Dec. 9, 1905, [date applied for under Patents Act, 1901]. Gas and like engines, igniting in. The sparking- plug described is intended chiefly for magneto ignition, and is characterized by the fact that those parts between which the sparks pass can be adjusted relatively without moving the central rod longitudinally. - The sparking end of the central rod is provided with plane surfaces, so that the sparking distance can be varied by simply rotating the central rod. The arrangement is intended to facilitate cleaning and to take up wear. The insulating-body a is of porcelain, steatite, or other suitable substance, and is secured, by a nut h, in the metal body b, the screwed end c of which is extended and slotted so as to present four sparking-surfaces d, e, f, g, Fig. 3. The other sparking- surfaces 1, 2, 3, 4 are formed by the rectangular piece k which is screwed on to the conductor j, the latter being held in place by a nut m and elastic washer n to allow of expansion. An inner chamber is provided to obviate fouling. The sparking-surfaces may take the form shown in Fig. 4. In either case, they are relatively large and project outside the body of the plug ; adjustment of the sparking distances may be readily made by the insertion in one of them of a knife blade or screwdriver.