100 



FARADAY 



ing of the flame of a lamp, but it will apply to the flame of a 

 candle. The cup of the candle is the vessel or lamp ; the melted 

 spermaceti is the oil ; and the wick is common to both. Upon 

 that he sets this little flame, and then he represents what is 

 true, a certain quantity of matter rising about it which you 

 do not see, and which, if you have not been here before, or 

 are not familiar with the subject, you will not know of. He 

 has here represented the parts of the surrounding atmosphere 

 that are very essential to the flame, and that are always pres- 

 ent with it. There is a current formed, which draws the 

 flame out; for the flame which you see is really drawn out 

 by the current, and drawn upward to a great height, just as 

 Hooker has here shown you by that prolongation of the cur- 

 rent in the diagram. You may see this by taking a lighted 

 candle, and putting it in the sun so as to get its shadow 

 thrown on a piece of paper. How remarkable 

 it is that that thing which is light enough to 

 produce shadows of other objects can be made 

 to throw its own shadow on a piece of white 

 paper or card, so that you can actually see 

 streaming round the flame something which 

 is not part of the flame, but is ascending and 

 drawing the flame Upward. Now I am going 

 to imitate the sunlight by applying the voltaic 

 battery to the electric lamp. You now see our 

 sun and its great luminosity; and by placing 

 a candle between it and the screen, we get the 

 shadow of the flame., You observe the shadow 

 of the candle and of the wick; then there is 

 a darkish part, as represented in the diagram, 

 and then a part which is more distinct. Curi- 

 ously enough, however, what we see in the 

 shadow as the darkest part of the flame is, in reality, the 

 brightest part; and here you see streaming upward the 

 ascending current of hot air, as shown by Hooker, which 

 draws out the flame, supplies it with air, and cools the sides 

 of the cup of melted fuel. 



I can give you here a little farther illustration, for the pur- 

 pose of showing you how flame goes up or down according 

 to the current I have here a flame it is not a candle flame 



FIG. 58 



