To begin with, he considered that he could not enjoy a more splendid opportunity to give children a taste for science and to stimulate their curiosity than by finding a means to interest them, from their earliest infancy, in their simple playthings, even the crudest and most inexpensive; so true is it that "in the smallest mechanical device or engine, even in its simplest form, as conceived by the industry of a child, there is often the germ of important truths, and, better than books, the school of the playroom, if gently disciplined, will open for the child the windows of the universe."

"The humble teetotum, made of a crust of rye-bread transfixed by a twig, silently spinning on the cover of a school-book, will give a correct enough image of the earth, which retains unmoved its original impulse, and travels along a great circle, at the same time turning on itself. Gummed on its disc, scraps of paper properly coloured will tell us of white light, decomposable into various coloured rays...

"There will be the pop-gun, with its ramrod and its two plugs of tow, the hinder one expelling the foremost by the elasticity of the compressed air. Thus we get a glimpse of the ballistics of gunpowder, and the pressure of steam in engines..."

The little hydraulic fountain made of an apricot stone, patiently hollowed and pierced with a hole at either side, into which two straws are fitted, one dipping into a cup of water and the other duly capped, "expelling a slender thread of water in which the sunlight flickers," will introduce us to the true syphon of physics.

"What amusing and useful lessons" a well-balanced scheme of education might extract from this "academy of childish ingenuity"! [(5/6.)]

At this time he was undertaking the education of his own children. His chemistry lessons especially had a great success. [(5/7.)] With apparatus of his own devising and of the simplest kind, he could perform a host of elementary experiments, the apparatus as a rule consisting of the most ordinary materials, such as a common flask or bottle, an old mustard-pot, a tumbler, a goose-quill or a pipe-stem.

A series of astonishing phenomena amazed their wondering eyes. He made them see, touch, taste, handle, and smell, and always "the hand assisted the word," always "the example accompanied the precept," for no one more fully valued the profound maxim, so neglected and misunderstood, that "to see is to know."

He exerted himself to arouse their curiosity, to provoke their questions, to discover their mistakes, to set their ideas in order; he accustomed them to rectify their errors themselves, and from all this he obtained excellent material for his books.

For those more especially intended for the education of girls he took counsel with his daughter Antonia, inviting her collaboration, begging her to suggest every aspect of the matter that occurred to her; for instance, in respect of the chemistry of the household, "where exact science should shed its light upon a host of facts relating to domestic economy" [(5/8.)], from the washing of clothes to the making of a stew.

Even now, to his despair, although freed from the cares of school life, he was always almost wholly without leisure to devote himself to his chosen subjects.