CH. V] MAGIC LANTERN WITH PETROLEUM LAMP 123 



for getting the best draught when the lamp is turned up full 

 height. 



The reflector is a concave mirror placed with its center of curva- 

 ture coinciding with the flame. This serves to reflect the backward 

 extending light to a focus on the flame again, and from thence it 

 passes onward to the condenser with the rays passing directly from 

 the flame to the condenser. 



FIG. 66. MULTIPLE-WICK, PETROLEUM LAMP FOR THE MAGIC LANTERN. 

 (From the Catalogue of the Mclntosh Battery and Optical Company, 7889). 



This figure shows that there is a single oil reservoir but four separate wicks, 

 each with a mechanism for turning the wick up or down. It also shows 

 clearly the inclination toward each other of the separate wick holders, and 

 finally that the lamp has a single chimney. 



The openings in the metal chimney for the reflector and the con- 

 denser must be covered with glass or with clear mica or the lamp 

 will smoke. 



198. Management of the lamp. Before an exhibition the 

 reservoir is filled nearly full with good petroleum (kerosene oil). 

 The wicks must be carefully trimmed until the flame burns without 

 tails. One must be careful in preparing the lamp not to get any 

 oil on the outside, for when the lamp gets hot this oil is sure to smell 

 badly. 



