ases in weight, and smells like licorice. When put into
cold water it gives a sweetish bitter taste, not unlike coffee."

"Let me try some of it, and don't say anything about it to Harry. And
now, while I think about it, why couldn't we make some crocks out of our
clay, so we can use them for our milk. We can't put them in the copper
vessels and the iron is just as bad."

"That is a splendid idea; and you might as well vitrify them."

"What do you mean by vitrifying them?"

"Putting the glaze on them, just like the common crocks have."

"That would be simply fine."

The Professor explained the process, which consisted in making the
crocks out of the best clay available, and then burning them. Afterwards
an intense heat must be made in the furnace, and after soaking the
crocks in a strong solution of salt brine, they must be put in and
burned again; the greater the heat, the better.

The boys started at this with a will, and when they had arranged to make
the crocks they found it most difficult to put them into a round and
uniform shape.

"I would suggest that you make a potter's wheel for that purpose."

"A potter's wheel? What is it like?"

"It is the simplest thing imaginable. Do you think, Harry, you could
turn out a wooden vessel just the size of the outside of an ordinary
milk crock, and turn it with a central stem below, and also have a
little pulley on that stem?"

The Professor made a drawing (Fig. 29), which shows just how he wanted
it made. In the drawing, A is the cup-shape, which is the size and shape
of outside the crock; B is the central stem; and D is the small pulley
on the stem. This was mounted in a pair of arms like CC, and a belt was
attached to the pulley.

"You have made a very creditable article. Now you may make a flat
paddle, and shape one end so that it will be just like the inside of the
crock."

[Illustration: _Fig. 29. Potters Wheel._]

The drawing (Fig. 30) shows how it was made, with a cross handle at the
upper end.

That day the crocks were turned out in the following manner: The
potter's wheel was rotated about sixty turns a minute, and the clay, in
a plastic state, was put in the cup-shaped top, and the hands used to
force the clay up the side wall. When the crock was formed in as even a
manner as it could be by hand, the blade described was used to make the
interior uniform.

The potter's wheel is one of the oldest tools known. Its use can be
traced back for more t