was that the numerous sparks from the fire had
such long fiery tails. Another was that the frost so quickly froze up
the large pieces of meat, that often had to be thawed out two or three
times at each meal. Another was that the ice often formed on their cups
of tea, which had been taken boiling hot out of the kettle only a few
minutes before. Then they were startled by sharp reports, like pistol
or musket shots, that they kept hearing from places in the dark forest
all around them, as though some lurking savages were taking snap shots
at them. Two especially were so near, and so real, that Sam jumped up
so suddenly that he spilled his tea over the tablecloth.

"Faith, indeed," he exclaimed, "I don't want to be potted out here by
any wild huntsmen, or Northern desperado, or red Indian."

The other boys were also much startled, but Mr Ross quieted their fears
by telling them that these sounds were caused by the bursting in the
trees, as the result of the freezing sap. Water in freezing always
expands, and as there is sufficient sap in some trees, when it freezes,
it bursts them. It must expand, and tremendous is its power, as even
the burst rocks show.

"It is a good thing that the ice remains on the top of the water," said
Frank. "As it freezes it expands, and thus, being lighter than the
water, it comes to the top."

"What a mess we would be in," said Sam, "if as the ice froze in chunks
it sank to the bottom and kept at it all winter. Sure then, before
spring, in such a land as this, the lakes and rivers would all be one
solid mass of ice, and then what would become of the fish and us?"

"A sensible remark, Sam, and characteristically put," said Mr Ross.
"If the ice were heavier than the water, and continued sinking, the
colder regions would continually be encroaching on the warmer, to such a
degree that in time the earth's habitable portions would be very much
diminished."

"Why is it," said Alec, "that the milk which we are carrying in chunks,
wrapped up in paper bags, when put into our cups of tea, does not melt
as soon as do the lumps of white sugar of the same size?"

"Closely examine a lump of frozen milk, and also a lump of sugar, and
you will easily see the reason," said Mr Ross. "When milk is firmly
frozen it is very solid indeed--so solid that even hot water can only
melt it on its surface. With a lump of sugar it is very different, as
on account of its porousness the water at once forces its