oint to
the poles."

"But suppose we should be on the sea, and would not have anything else
to guide us, what would there be to show which way is north and which
direction south?"

"Sirius is easily distinguished, because it is, apparently, the largest
of all the fixed stars. It cannot be mistaken. By taking that as a
starting point, and following with the eye along past Canopus, you will
be looking to the south pole."

"Isn't Sirius called the Dog Star? And hasn't it some connection with
the dog days?"

"Yes; in the remote ages of the world, when every man was his own
astronomer, the rising and setting of this star was watched with deep
solicitude. The astronomers of Egypt determined the length of the year
by the number of its risings. It foretold to them the rising of the
Nile, which they called Siris, and admonished them when to sow. At that
season of the year Sirius rises with the sun, and owing to its intense
brilliancy, the ancients supposed that it blended its heat with the sun
and thus was the cause of the intense heat; hence during that time were
called dog days. At present what are so designated are the days between
the 3d of July to the 11th of August."

CHAPTER VIII

THE CATARACT AND ITS MARVELS

The tramp through the forest was a leisurely one, as constant stops were
made to examine the country. The rescued boys were wonderfully
recuperated by the influence of two days of good food and the peace of
mind and contentment that had come into their lives after a stormy and
hazardous fourteen months' struggle.

Ralph brought in several specimens of fruit and vegetables, of the kind
they had seen the natives use, and one specimen which had a long,
tapering root. "Here is something they always had on hand," he remarked
as he handed it to the Professor.

"That would be a valuable addition to our vegetable diet. It is a
species of Salsify, or vegetable oyster, and by some called Goat's
beard, on account of the peculiar top."

"I should like to know what this is. It seems to me that we saw plants
of the same kind down near the South River." George produced a plant
with beautiful large leaves at the end of each stem, which grew in
clusters.

The Professor smiled. "You have at last found the real rubber tree. This
was taken from one of the small trees, but they grow to considerable
height, and many of the trees yield about eight gallons of milk, when
first cut, which produces two pounds of rubber