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
Saturday 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 upwards 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 direction, my cup would be lop-sided,
and the fluid would consequently run over,--for the same force of gravity