r, which walk or crawl on the earth or burrow
beneath it; and I have the means of shooting them or trapping them.
Those I can, I hope to preserve alive; and if not, to be able to exhibit
to my scientific friends, when I return home, the forms of some perfect,
the skins of others, and the skeletons of others. And now, having told
you thus much, I must leave you to guess what I profess myself to be.
One thing I can tell you, I know very, very little compared to what
there is to be known. I hope to gain more knowledge but I am very well
aware that, gain all I can, I can but add a very small portion to what
is already known, and a still smaller compared to what is to be
ascertained. Here comes the captain. We are old friends, and that
induced me to select this ship for my voyage. Are you his son?"

"No, sir," I answered; "but he is a very kind friend of mine; and were
it not for him, I know not what would have become of me and my sister."

The _Bussorah Merchant_ had a fine passage down Channel, and taking her
departure from the Land's End, stood across the Bay of Biscay. Four
days afterwards the captain told us that we were in the latitude of Cape
Finisterre, but no land was to be seen. Another eight days, with the
wind abeam, carried us into the neighbourhood of the island of Madeira.

"Would not it be as well to have a look at it, sir," I said, "and then
we shall better know where we are."

The captain smiled. "That is not at all necessary," he answered. "By
the observations we are able to take with the perfect instruments we
possess, we are able at all times to ascertain our exact position on the
ocean; and we might thus sail round either Cape Horn or the Cape of Good
Hope to New South Wales without once sighting land till we were about to
enter Port Jackson."

"It is very wonderful," I said. "What puzzles me is how you can find
the longitude. I know you get the latitude by seeing how high the sun
is above the horizon at noon, and then with the aid of the nautical
almanac you can easily work out the calculation."

"With the aid of the chronometer we can as easily ascertain the
longitude, though the calculation is a little longer," answered Captain
Davenport. "I can explain it to you more easily. The chronometer shows
us the exact time at Greenwich. We know by our nautical almanac that,
at a certain hour on a certain day, the sun will have attained at
Greenwich a certain altitude. When on that day and