This hole should be left with the middle exalted, and the circumfere dug more deeply.

Then let him fill it with saltpetre, all save a little space in the midst, where the boss of the wood is.

Upon that boss (and it will be the better if a splinter of timber rise upward) he sticks the end of his candle of tallow, or 'rat's tail,' as we called it, kindled and burning smoothly.

Anon, as he reads by that light his lesson, lifting his eyes now and then it may be, the fire of candle lays hold of the petre with a spluttering noise and a leaping.

Then should the pupil seize his pen, and, regardless of the nib, stir bravely, and he will see a glow as of burning mountains, and a rich smoke, and sparks going merrily; nor will it cease, if he stir wisely, and there be a good store of petre, until the wood is devoured through, like the sinking of a well-shaft.