04 FARADAY 



means, and then light the top of the wick. When the flame 

 runs down the cotton to the oil, it gets extinguished, but it 

 goes on burning in the part above. Now I have no doubt 

 you will ask how it is that the oil which will not burn of 

 itself gets up to the top of the cotton, where it will burn. We 

 shall presently examine that; but there is a much more 

 wonderful thing about the burning of a candle than this. 

 You have here a solid substance with no vessel to contain 

 it; and how is it that this solid substance can get up to the 

 place where the flame is? How is it that this solid gets 

 there, it not being a fluid? or, when it is made a fluid, then 

 how is it that it keeps together? This is a wonderful thing 

 about a candle. 



We have here a good deal of wind, which will help us in 

 some of our illustrations, but tease us in others ; for the sake, 

 therefore, of a little regularity, and to simplify the matter, I 

 shall make a quiet flame, for who can study a subject when 

 there are difficulties in the way not belonging to it? Here 

 is a clever invention of some costermonger or street- stander 

 in the market-place for the shading of their candles on Sat- 

 urday nights, when they are selling their greens, or potatoes, 

 or fish. I have very often admired it. They put a lamp- 

 glass round the candle, supported on a kind of gallery, which 

 clasps it, and it can be slipped up and down as required. By 

 the use of this lamp-glass, employed in the same way, you 

 have a steady flame, which you can look at, and carefully 

 examine, as I hope you will do, at home. 



You see then, in the first instance, that a beautiful cup is 

 formed. As the air comes to the candle, it moves upward 

 by the force of the current which the heat of the candle 

 produces, and it so cools all the sides of the wax, tallow, or 

 fuel as to keep the edge much cooler than the part within; 

 the part within melts by the flame that runs down the wick 

 as far as it can go before it is extinguished, but the part on 

 the outside does not melt. If I made a current in one direc- 

 tion, my cup would be lop-sided, and the fluid would con- 

 sequently run over; for the same force of gravity which 

 holds worlds together holds this fluid in a horizontal position, 

 and if the cup be not horizontal, of course the fluid will run 

 away in guttering. You see, therefore, that the cup is 



