temperatures and densities, and moving in various ways. All these physical experiences pass up to the brain and produce some impression there. They do not constitute knowledge; a man may dabble in water all his life and remain ignorant of hydrostatics as a fish; but they do form the unconscious material which, when he comes to study hydrostatics later on, will make his knowledge living and real, not shadowy.
When a child's attention is attracted by any unfamiliar occurrence, especially by any such sound as that of a singing flame, or by a moving light on the ceiling, do not unnecessarily distract him. As long as he is interested and happy, leave him alone. Let him acquire the habit of quiet and silent observation.
As preparation for learning electricity, do not be satisfied with once showing the child that sealing-wax rubbed on flannel will attract bits of paper, but let him have a stick of wax, or better, a common vulcanite comb and a piece of flannel, and keep them, and try all the experiments he wants to try. Let him learn by experience that after a time the comb discharges and needs to be rubbed again; that if he touches the table with the charged comb it discharges at once and he has the labour of rubbing over again. As soon as he can be
