A Queer Candlestick.
Take a short piece of candle, and into its lower end thrust, by way of ballast, a nail. You should choose a nail of such a size that the candle-end shall be all but immersed, the water just rising to its upper edge, though not so high as to overflow the top and wet the wick. Now, light the candle, and you may safely make a wager that, in spite of the apparently unfavorable circumstances in which it is placed, it will burn completely to the end.
This may, at first sight, appear a rash assertion, but after a little reflection, you will see how the arrangement works. The candle, of course, grows shorter as it burns, and it seems therefore as if the water must overflow the top and reach the wick; but on the other hand, it grows proportionately lighter, and therefore rides higher in the water.
Further, the external surface of the candle, kept cool by the surrounding liquid, melts much more slowly than it would in the open air, so that the flame hollows out for itself a sort of little well, as represented in the right-hand corner of our illustration.
This hollowing process further lightens the candle, and the wick will, as you have stated, burn to the very end.