frozen, you simpleton, notwithstanding it has
boiled. Was it boiling, Sir, eh? when you
took it off the fire? That is the question, Sir."

"Yes, Sir, that was what I mean to say,
Sir," replied Thomas.

"Mean to say, Sir! Then why didn't you
say it, Sir? Eh? There—no, don't put it on,
Sir; hold it still. Harry, reach me the
thermometer," said Mr. Bagges, putting on his
spectacles. " Let me see. The boiling point
of water is two hundred and—what?"

"Two hundred and twelve, Fahrenheit,"
answered Master Wilkinson, "if commonly
pure, and boiled in a metallic vessel, and
under a pressure of the atmosphere amounting
to fifteen pounds on every square inch of
surface, or when the barometer stands at
thirty inches."

"Gracious, what a memory that boy has!"
exclaimed his uncle. " Well; now this water
in the kettle—eh?—why, this is not above
one hundred and fifty degrees. There, Sir,
now set it on the fire, and don't bring me up
cold water to make tea with again; or else,"
added Mr. Bagges, making a vague attempt
at a joke, " or else—eh?—you will get yourself
into hot water."

Mr. Thomas was seized with a convulsion
in the chest, which he checked by suddenly
applying his open hand to his mouth, the
effort distending his cheeks and causing his
eyes to protrude in a very ridiculous manner,
whilst Mr. Bagges disguised his enjoyment of
the effects of his wit in a cough.

"Now let me see," said the old gentleman,
musingly contemplating the vessel simmering
on the fire; "how is it, eh, Harry, you said
the other day that a kettle boils?"

"La!" interrupted Mrs. Wilkinson, who was
of the party, "why, of course, by the heat of
the coals, and by blowing the fire, if it is not
hot enough."

"Aha! " cried her brother, " that's not the
way we account for things, Harry, my boy,
eh? Now, convince your mother; explain
the boiling of a kettle to her: come."

"A kettle boils," said Harry, " by means of
the action of currents."

"What are you talking about? Boiling a
plum-pudding in a tea-kettle!" exclaimed the
mystified mamma.

"Currents of heated particles—of particles
of hot water," Harry explained. " Suppose
you put your fire on your kettle—on the lid
of it—instead of your kettle on your fire,
—what then?"

"You would be a goose," said his mother.

"Exactly so—or a gosling,"—rejoined her
son; " the kettle would not boil. Water is a
bad conductor of heat. Heat passes through
the substance of water with very great
difficulty. Therefore, it would have a hard matter
to get from the top of a kettle of water to the
bottom. Then how does it so easily get from
the bottom to the top?"

"All! " sighed Mr. Bagges. " In my young
days we should have said, because the heat
rises, but that won't do now. What is all
that about the—eh—what law of ex—what?
—pansion—eh?"

"The law of expansion of fluids and gases
by heat. This makes the currents that I
spoke of just now, mamma; and I should
have spelt the word to explain to you that I
didn't mean plums. You know what a
draught is?"

"I am sorry to say I do," Mr. Bagges
declared with much seriousness, instinctively
carrying his hand to the region of the human
body from the Latin for which is derived the
term, Lumbago.

"Well," pursued Harry, " a draught is a
current of air. Such currents are now
passing up the chimney, and simply owing
to that trifling circumstance, we are able
to sit here now without being stifled and
poisoned."

"Goodness!" ejaculated Mrs. Wilkinson.

"To be sure. The fire, in burning, turns
into gases, which are rank poison—carbonic
acid, for one; sulphurous acid, for another.
Hold your nose over a shovelful of hot cinders
if you doubt the fact. The gases produced
by the fire expand; they increase in bulk
without getting heavier, so much so that they
become lighter in proportion than the air, and
then they rise, and this rising of hot air is
what is meant by heat going upwards. The
currents of hot air that go up the chimney in
this way have currents of cold air rushing
after them to supply their place. When you
heat water, currents are formed just as when
you heat gas or air. The heated portion of
water rises, and some colder water comes
down in its place; and these movements of
the water keep going on till the whole bulk
of it is equally hot throughout."

"Well, now," interrupted Mr. Bagges, " I
dare say this is all very true, but how do you
prove it?"

"Prove that water is heated by the rising
and falling of hot currents? Get a long,
slender glass jar. Put a little water, coloured
with indigo, or anything you like, into the
bottom of it. Pour clear water upon the
coloured, gently, so as not to mix the two,
and yet nearly to fill the jar. Float a little
spirit of wine on the top of the water, and set
fire to it. Let it blaze away as long as you
like; the coloured water will remain steady
at the bottom of the jar. But hold the flame
of a spirit-lamp under the jar, and the
coloured water will rise and mix with the
clear, in very little time longer than it would
take you to say Harry Wilkinson."

"Ah! So the water gets coloured through-
out for the same reason that it gets heated
throughout," Mr. Bagges observed, " and
when it gets thoroughly hot—what then?"

"Then it boils. And what is boiling?"

"Bubbling," suggested the young
philosopher's mamma.

"Yes; but ginger-beer bubbles," said Harry,
"but you wouldn't exactly call that boiling.