ack, so that there would be no
reflecting of light inside. It is better--he told the boys--to paint the
inside, if possible, after the tube is made, because the rolling and
pounding in shaping and soldering the tube are likely to make the paint
crack off. Then he took out of his pocket a paper, and unrolled a round
spectacle glass, just big enough to slip into the end of the larger
tube. "What's that?" the children exclaimed, all at once. "This is the
object-glass of our telescope," was the answer. "The light from the
object comes through this into the tube. It is a thirty-six-inch glass;
that is, it brings the rays together at a distance of thirty-six
inches." Frank held it up to the sun, which was getting low, and when
the rays began to burn his hand, Walter brought the yard-stick, and it
was just about thirty-six inches from the glass to the spot on his hand
where he felt the heat. That was the _focus_ of the glass. While the
boys were wondering how the object-glass was to be fastened into the
tube, the parson was already doing it. He had the tinman cut slits in
the end about an eighth of an inch wide and almost twice as deep. Every
other one of these he doubled back inside the tube, and pressed down
with pincers, so that there should be nothing sticking out in the way of
the moon and stars if they should try to get in. These made a rest for
the glass, so that it couldn't slip into the tube. Then he bent the
other slits down over the edge of the glass, but not so as to shut out
any light, and these slits held the glass firmly.

The boys, of course, now wished to see whether the steeple of the church
looked any bigger through this tube and object-glass. They couldn't see
it so well as with the naked eye, and feared the new telescope was a
failure. But their father told them it was too soon yet to vote on that
question. He told Frank to hold out his hand, and see whether the sun
would burn his hand through the glass and tube, as it did through the
glass alone. It did. "Now," said he, "if you hold this tube up to
Jupiter, at thirty-six inches from the glass there will be a very small
image of him and his moons. If we could only see that image or picture
through a microscope, we might see the moons as plainly as we see
Jupiter himself with the naked eye."

"Why won't our microscope do?" asked Walter.

The parson said we couldn't get the image and the microscope together
rightly; but while he was explaining, he was also