Edwards’ Condenser System.
This system differs from the foregoing in that the spark-gaps are connected in multiple, instead of series, and each burner is provided with a small but efficient condenser.
Fig. 38.
It prevents trouble should a wire break between burners, in which event only one burner would be out of commission, whereas in the first method, the whole number in that series would suffer. It is also more sure in action and presents less liability of the spark jumping to the ground. The burner pillars need not be made of porcelain or lava; in fact, the electrodes can be readily attached to the existing burner. Fig. 38 is a condenser consisting of a small oval piece of mica, on each side of which is fastened, with insulating varnish, a spatula-shaped piece of tinfoil. One foil sheet is attached to the line, the other to the burner electrode. These condensers must not be allowed to get wet or their efficiency will be impaired.
Fig. 39. & Fig. 40
Figs. 39 and 40 are the most generally used burners, the wire from the condenser being attached to the lug or top electrode, which is insulated from the burner by means of the mica plate to which it is riveted. The burner pillars are of course grounded through their being screwed into the gas pipe. The circuit is shown in Fig. 41. I is the induction or Ruhmkorff coil, in the primary circuit of which is the key, K, controlling the current from the battery, B, and across which is bridged the condenser, C C. When the coil vibrator is used, the condenser C C can be omitted, that of the coil itself serving instead. S is the wire leading from the secondary terminal of the coil to the burner condenser, C, which, in turn, are connected to the electrodes on the burners, P P, as before noted. The other secondary wire is grounded preferably to the gas pipe itself.
Fig. 41.
Where a lot of burners are placed together, as in a ring, it is often feasible to light them by contagion, one tip only being connected to the coil circuit, the others lighting from it and conveying the flame around to the rest. This avoids multiplicity of circuits, or, perhaps, too many burner gaps on one circuit; but the one burner may fail to light, whereas, where all are fitted, the chances of failure are less, especially in the Edwards condenser system.