for weights?" asked Rollo.

"O, weights!--yes, you must have some weights. You must make them of
lead. I will show you how."

So the apothecary took a small piece of sheet lead, rather thin, and cut
off a little square of it. He then put it into one of his scale
balances, and put a thin, square weight of brass, similar to it, into
the other scale. The lead weight was a little too heavy. He then clipped
off a very little with his scissors. This made it about right. Then,
with the point of his scissors, he scratched a figure 1 upon it.
"There," said he, "boys, there is a standard for you."

"What is a standard?" said Rollo, taking up the weight.

"Why, it is a weight made exactly correct, for you to keep, and make
yours by. It is a _one-grain_ weight. I will give you some sheet lead,
and when you get home and have made your scales, you can cut off another
piece, and weigh it by that, and so you will have two one-grain weights.
Then you can put those two into one scale, and a piece of lead as big as
both of them into the other scale, and when you have made it exactly as
heavy as both of the others, you must mark a figure 2 upon it, and then
you will have a _two-grain_ weight. In the same way you can make a
_five-grain_ weight, and a _ten-grain_ weight, and a pennyweight."

"What is a pennyweight?" said Rollo.

"It is a weight as heavy as twenty-four grains."

"The pennyweight will be very big, then," said Rollo.

"Yes," said the apothecary; "but you can take a little strip of lead
like a ribbon, and then roll it up, when you have made it just heavy
enough, and then it will not take up much room. So you can make another
roll for two pennyweights, and another for five pennyweights, and
another for ten pennyweights."

"And another for twenty pennyweights," said James.

"Yes; only twenty pennyweights make an ounce. So you will call that an
_ounce_ weight. But you cannot weigh more than an ounce, I should think,
in your knitting-needle scales."

By this time the apothecary had put up the medicines, and he gave them
to Rollo. There was a middle-sized parcel, and a very small parcel, and
small, round box. Rollo put them all into the pocket of his pantaloons.
Then he opened his wallet, and took out the bill, and gave it to the
apothecary. The apothecary handed him the change. It was half a dollar,
and one small piece of silver besides. Rollo put the change back into
the wallet, and tied it up just as it had been befor