e for a week."

It would have been ungracious to refuse him. His wish was complied with.
A sufficient quantity of chlorate of potash and caustic potash was
placed at his disposition, with provisions for a week; then having
shaken hands with his friends, on the 12th of November at 6 a.m., after
having expressly recommended them not to open his prison before the 20th
at 6 p.m., he crept into the projectile, the iron plate of which was
hermetically shut.

What happened during that week? It was impossible to ascertain. The
thickness of the projectile's walls prevented any interior noise from
reaching the outside.

On the 20th of November, at six o'clock precisely, the plate was
removed; the friends of J.T. Maston were rather uneasy. But they were
promptly reassured by hearing a joyful voice shouting a formidable
hurrah!

The secretary of the Gun Club appeared on the summit of the cone in a
triumphant attitude.

He had grown fat!

CHAPTER XXIV.

THE TELESCOPE OF THE ROCKY MOUNTAINS.

On the 20th of October of the preceding year, after the subscription
list was closed, the president of the Gun Club had credited the
Cambridge Observatory with the sums necessary for the construction of a
vast optical instrument. This telescope was to be powerful enough to
render visible on the surface of the moon an object being at least nine
feet wide.

There is an important difference between a field-glass and a telescope,
which it is well to recall here. A field-glass is composed of a tube
which carries at its upper extremity a convex glass called an
object-glass, and at its lower extremity a second glass called ocular,
to which the eye of the observer is applied. The rays from the luminous
object traverse the first glass, and by refraction form an image upside
down at its focus. This image is looked at with the ocular, which
magnifies it. The tube of the field-glass is, therefore, closed at each
extremity by the object and the ocular glasses.

The telescope, on the contrary, is open at its upper extremity. The rays
from the object observed penetrate freely into it, and strike a concave
metallic mirror--that is to say, they are focussed. From thence their
reflected rays meet with a little mirror, which sends them back to the
ocular in such a way as to magnify the image produced.

Thus in field-glasses refraction plays the principal part, and
reflection does in the telescope. Hence the name of refractors given to
the f