6 THE PRODUCTION AND USE OF LIGHT 



mable and dangerous. Up to about 1860 candles were by far 

 the safest and best sources of artificial light which the world 

 had ever used. 



It was in August, 1858, that the first successful oil well was 

 sunk in Pennsylvania. Petroleum had been known for a 

 long time, but it had never before been found in commercial 

 quantities and little use had been made of it except as medicine. 

 Soon after it was obtained in large quantities, the discovery 

 was made that an oil could be obtained from crude petroleum 

 which would burn freely and still be safe to handle. This 

 new oil was called KEROSENE, though some people, sup- 

 posing that it came from coal, called it COAL OIL. We still 

 sometimes hear it called by that name. Inventors soon made 

 lamps well suited for the burning of this oil. The common 

 kerosene lamp of today is, in principle, exactly like those 

 earliest lamps. 



8. Parts of the Kerosene Lamp. The ordinary kerosene 

 lamp really consists of three parts: (1) The BOWL for contain- 

 ing the oils; (2) the WICK; (3) the BURNER AND CHIMNEY. 

 The wick is usually made of soft, loosely woven cotton 

 cloth. What is its purpose? What does it do? 



Burners vary much in construction, but all have certain 

 necessary parts, namely: (1) The CAP, OR CROWN; (2) the 



PERFORATED BASE; (3) the TUBE FOR THE WICK. 



Exercise 4. The Use of the Burner and Chimney 



Examine a burner carefully and discover these parts. Make a 

 sketch in your notebook of your burner showing clearly each of these 

 parts. Label all parts of your sketch somewhat as the sketch, Fig. 

 6, is labeled. Do not copy the sketch from the book but sketch your lamp. 



Study carefully the device for regulating the height of the wick. 



Light the lamp, place the chimney in position, and observe the 

 steadiness of the flame. If there is not much draft through the room 

 there should be very little flickering of the flame. It should burn 

 with a steady flame. 



Wave your book past the bowl of the lamp so as to produce a 

 strong gust of air against the under side of the burner. What is the 

 effect upon the flame? Can you tell why it becomes smoky? Did 



