enough, I believe," said Tom. "You get a sheet of
tinfoil, lay it on a table, cover it with quicksilver, and then put the
glass on it, and press it with weights till the tinfoil and quicksilver
stick to the glass, and then you have a regular mirror."

"You seem to know all about it, Tom," said the Vicar, who had dropped in
for a chat, and to hear how the telescope was going on.

"I read it somewhere," said Tom.

"And he can always recollect this sort of thing," said his uncle; "but
never could remember anything to do with the law."

Tom looked at him reproachfully.

"Well," continued Uncle Richard, "your process would do for ordinary
looking-glasses, Tom, but not for an optical reflector."

"Why, uncle?"

"Because the rays of light would have to pass through the thickness of
the glass before they reached the reflecting surface,--the
quicksilver,--and in so doing they would be refracted--broken-up and
discoloured--so that the reflection would most likely be doubled when it
came away; that is, you would see one reflection from the silver at the
back, and another from the surface of the glass."

"Therefore," said the Vicar, "we must decline friend Tom's ingenious
proposal, and take yours, Brandon, for as usual you have a plan ready."

"Well, yes," said Uncle Richard, smiling; "but it is due to the
inventor. We must silver the glass, but on the surface, so as to get a
reflection at once. Are you going to stay, Maxted?"

"If I may," was the reply.

"Very well; but for experiment, as it is all new to me, I think we will
try first to silver one of these pieces of the broken speculum. Yes;
that largest piece."

The conversation took place in the workshop, and the triangular piece of
glass having been brought out, it was first thoroughly washed, and
rinsed with rain-water, and then further cleaned by rubbing it well with
a strong acid, so as to burn off any impurity, and after another rinsing
in clear rain-water it was declared by Uncle Richard to be chemically
clean.

"A good thing to be chemically as well as morally clean, Tom," said the
Vicar, smiling; "but I'm not going to stand here without asking
questions if you don't, Master Tom. First then, why must the glass be
chemically clean?"

"So that the silver may adhere to it," said Uncle Richard, who was now
carefully arranging the freshly-cleaned glass, so that it lay on two
pieces of wood in a shallow tray half full of water.

"My turn to question," s