A. They used to place a soft iron nail upon their anvil; strike it two or three times with a hammer; and the point became sufficiently hot to light a brimstone match.
Q. How can a nail (beaten by a hammer) ignite a brimstone match?
A. As the particles of the nail are compressed by the hammer, it cannot contain so much heat as it did before; so some of it flies out (as water flows from a sponge when it is squeezed).
Q. Why does striking a flint against a piece of steel produce a spark?
A. The blow condenses those parts of the flint and steel which strike together, and squeezes out their latent heat.
Q. How does this development of heat produce a spark?
A. A very small fragment (either of the steel or flint) is knocked off red-hot, and sets fire to the tinder on which it falls.
Q. Why is it needful to keep blowing the tinder with the breath?
A. Because blowing the tinder, drives the oxygen of the air towards it.