used by this movement produces the
heat."

"Is that true of all substances?"

"Yes."

"Well, if air is forced together will it heat in the same way?"

"Yes, and for the same reason. The tiny particles, of which air is
composed, move among each other with such rapidity, under compression,
that the heat their frictional contact develops is dependent on the
pressure exerted."

"You used the terms 'atom' and 'molecules' a moment ago. What is the
difference between them?"

"A molecule is always composed of two or more atoms. An atom is smaller
than a molecule, for this reason. Furthermore, an atom comprises only
one substance. A molecule has two or more substances in its make-up. For
instance, water is composed of two parts of hydrogen and one part of
oxygen. One molecule of water, therefore, has three atoms, two of the
atoms being hydrogen, and one atom oxygen."

"Baby," the infant orang-outan, had now grown to be a pretty good-sized
boy. He would sit at the table and gravely eat with a knife and fork,
which he had learned to handle most intelligently. In the various trips
which had been made from time to time, the Baby was kept at home, but on
more than one occasion he would follow up the wagon, and would as often
be welcomed when he did come.

Harry found a good use for him later on, and from that time forward Baby
knew that a jaunt into the forest meant a trip for him as well. When it
came to tree climbing Baby was in his glory. He would swing from branch
to branch, and shake the nuts, and the amusing thing was to see him help
gather and throw the nuts into the wagon, in the most business-like
fashion. He was never known to laugh, but they had many occurrences
which, no doubt, made him smile in his own way.

George was an adept cook. He was fond of making surprising delicacies,
and boy-like, they were always the kind that had honey of some sort in
their composition. Without any knowledge of cooking, but knowing, in a
general way, that eggs and milk were the principal things used in
puddings, it was not long before he was regarded as the chef. Baby was
sure to be present whenever George occupied the kitchen. And help! Why
certainly! He knew what flour meant, and particularly honey. The truth
is, that he knew what that meant if George merely looked in the
direction of the honey pot.

And talking about eggs! Harry found out about this accomplishment in
Baby. In the tall grass beyond the barley fields were flock