ed States is on the headlands of the Hawaiian
Islands. This is eight and three-quarters feet in diameter and is made
from the most carefully polished glass. And by the way, among other
uses that science makes of glass are telescopes, microscopes, and
field-glasses, which are all constructed from flawlessly ground lenses.
Often it takes a whole year, and sometimes even longer, to polish a
large telescope lens. Without this magnifying agency we should have no
astronomy, and fewer scientific discoveries than we now have. The
glasses people wear all have to be ground and polished in much the same
fashion; opera glasses, magic lanterns, and every contrivance for
bringing distant objects nearer or making them larger are dependent for
their power upon glass lenses."

"Even when making glass I never dreamed it could be used for so many
different purposes," answered Giusippe.

"I wish we had counted up, as we went along, how many things it is used
for," Jean put in.

"We might have done so, only I am afraid you would have become very
tired had we attempted it," laughed Uncle Bob. "In addition to optical
glass there are still other branches of science that could not go on
without glass in its various forms. Take, for instance, electricity. It
would not be safe to employ this strange force without the protection
of glass barriers to hedge in its dangerous current. Glass, as you
probably know, is a non-conductor of electricity, and whenever we wish
to confine its power and prevent it from doing harm we place a layer of
glass between it and the thing to be protected. The glass checks the
progress of the current. In all chemical laboratories, too, no end of
glass test-tubes, thermometers, and crucibles are in demand for
furthering research work. Science would be greatly hampered in its
usefulness had it not recourse to glass in its manifold forms."

"What a wonderful material it is!" ejaculated Jean. "I never shall see
anything made of glass again without thinking of all it does for us."

"Be grateful, too, Jean, to the men who have discovered how to use it,"
replied Mr. Cabot gravely. "Certainly our mariners many a time owe
their safety to just such warning beacons as the one ahead. We must ask
the captain what light that is. Just think--to-morrow morning we shall
wake up in Boston harbor and be at home again."

A hush fell on the party.

"I shall be dreadfully sorry to have Miss Cartright leave us and go to
New York; sha'n'