ause instead of being at
the end, the hole will be in the side. Is that correct?"

"Quite right, and you are quite wrong, Tom, for you do not understand
the first simple truth in connection with a telescope."

"I suppose not, uncle," replied the lad, with a sigh. "I am very
stupid."

"No, you are not, sir, only about as ignorant as most people are about
glasses. I have explained the matter to you, but you have not taken it
in."

"I suppose not, uncle," said Tom, wrinkling his brow.

"Then understand it now, once for all. It is very simple if you will
try and grasp it. Now look here: what do you do with an ordinary
telescope or opera-glass, single or double? Hold it up to your eyes, do
you not?"

"Yes, uncle."

"And then?"

"Look through it at something distant, and it seems to draw it near."

"You do what?"

"Look through it, uncle."

"Nothing of the kind, sir, you do not."

Tom looked puzzled. What did his uncle mean? He had, he thought,
looked through a pair of field-glasses scores of times at home in the
old days.

"I make you stare, my lad, but I am glad to see it, for it shows me how
right I am, and that you do think as everybody else does who has not
studied optics, that you look through a glass at an object."

Tom stared harder, and once more the old idea came to him, and he asked
himself whether there were times when his uncle did not quite understand
what he was saying.

"But you do, uncle," he cried at last. Then he qualified this
declaration by saying, "Don't you?"

"No, my boy, once for all you do not; and if you take up any telescope,
and remove the eye-piece before looking along the tube, you will see
that your eyes will not penetrate the glass at the end. Then if you try
the eye-piece alone, you will find that you cannot even look through
that. How much less then will you be able to look through both at
once."

"But it seems so strange, uncle. You have a big magnifying-glass in a
tube, and don't look through it? Then what do you do?"

"Certainly not look through it, my boy."

"But the bigger the glasses are the more they magnify--the moon, say."

"Yes, Tom; and the more light they gather."

"Well, then, why do you say, uncle, that you don't look through the
glass?"

"Because it is a fact that I want you to understand," said Uncle
Richard, smiling. "The big glass, or in our case the reflecting
speculum, forms a tiny image of the object at which it is pointed, cl