where does the clay come from?"

"Nearly all from Sturbridge, in England. Some has been brought from Gay
Head, on Martha's Vineyard; but it doesn't answer like the imported."

Leaving the courteous artist in glass-pots to his labors, the party,
crossing again the breezy yard, entered a dismal brick-paved
basement-room, where grim bakers were attending upon a number of huge
ovens. One of these was just being filled; but instead of white and
brown loaves, golden cake, or flaky pies, the two attendants were piling
in short, thick bars of lead, and, hurry as they might, before they
could put in the last of the appointed number, little shining streams of
molten metal began to ooze from beneath the first, and trickle languidly
toward the mouth of the oven.

But our bakers were ready for them. With hasty movement they threw in a
quantity of moistened clay, shaping and compacting it with their shovels
as they went on, until in a very few moments they had completed a neat
little semi-circular dike just within the door, as effectual a barrier
to the glowing pool behind it, wherein the softened bars were rapidly
disappearing, as was ever the Dutchman's dike to the ocean, with whom he
disputes the sovereignty of Holland.

A wooden door was now put up, and the baking was left to itself for
about twenty-four hours, at the end of which time the lead would have
become transformed into a yellowish powder, known as massicot.

"You will see it here. They are just beginning to clear this oven," said
Cicerone, pointing to a row of large iron vessels which the workmen were
filling with the contents of the just opened kiln.

"And what next? What is it to the glass?" asked Miselle, unblushing at
her ignorance.

"Next, it is put into these other kilns, and kept in motion with the
long rakes that you see here, and at the end of forty-eight hours it
will have absorbed sufficient oxygen from the atmosphere to turn it from
massicot to minium, or red-lead. Look at this, if you please."

Cicerone here pointed to other iron vessels, in shape like the bowl out
of which the giant Blunderbore ate his bread and milk, while trembling
little Jack peeped at him from the oven; but these bowls were filled
with a beautiful scarlet powder of fine consistency.

"That is red-lead, one of the most important ingredients in fine
flint-glass, as it gives it brilliancy and ductility. But it is not used
in the coarser glasses. And here is the sand-room."

So