Fig. 6.
CHAPTER II.
Multiple Gas Lighting.
Fig. 7.
As we have already seen how a spark is exhibited at an interrupted contact, the means of its application to gas lighting will be considered. Fig. 7 represents the most generally used kind of electric gas burner or “pendant burner.” Its application is shown in Fig. 8. The wire W from the coil C is attached to the brass insulated collar carrying the contact S. The other wire from coil C and battery B is attached to the gas pipe G. As the burner is also screwed into the gas pipe itself, the circuit would be closed were it not for the gap at A on the burner, caused by the collar carrying the contact C and wire W, being insulated from the burner pillar P. When, however, a pull is given to the burner arm chain so as to cause the end of the spring R to strike contact C in passing, contact is made and broken, and a spark passes which ignites the gas issuing from the burner tip, the gas having previously been turned on. A piece of chain with a metal ball is attached to the burner arm in order to pull it down. In this class of burner there are many different makes differing only in minor details.
Fig. 8.
Fig. 9 shows a form of pendant burner which has no platinum contact, but has a broad lug on the insulated collar which is scraped against by the spiral spring when the arm is pulled down. It will be seen that the lug is not held by an insulated collar on the burner top, but is on the extension of an arm attached to the burner pillar by a large screw and insulating washers. The circuit wire goes under the smaller screw seen on the lower part of the contact arm, this forming a strong and neat form of attachment.