and here is a stone I
picked up, which I think is a flint," answered Boxall.

We could, however, find neither roots nor shrubs of any sort for fuel,
and were obliged to content ourselves with chewing some of the mussels
to stay our hunger as we walked along.

Having trudged on for some miles, some slight signs of verdure again
greeted our eyes, although the bushes rose scarcely a foot above the
ground. The branches, however, from their dry state, would, we
imagined, ignite; though it would require a large number of them to make
even a tolerable fire. We carried our fuel to a hole between two
sand-hills, hoping that the smoke, by the time it had ascended above
them, might become so attenuated as not to be observed by any passing
Arabs. The difficulty was how to light our fire. We required first the
means of striking a spark, and then the tinder to catch it, and finally
to produce a flame. Boxall tried with his knife and the stone he had
picked up, but was much disappointed when no spark proceeded from them,
the knife and stone producing only a light with a phosphoric appearance.
"We must not give it up, though," he said. "I have another idea--we
must form a burning-glass."

"How is that to be done?" I asked.

"Let me look at your watch, that I may compare it with mine," he said.
The glasses exactly corresponding in size, he took them both out.
"Now," he continued, "by filling the interior with water we shall have a
powerful burning-glass, which will in a few seconds set fire to any
inflammable substance, or burn a hole in our clothes."

I bethought me at that moment of the inside cotton-wool lining of my
cap, on which the rays of the sun had been beating all the morning, and
I felt sure that it would quickly catch fire; so teasing out a small
piece, I followed Boxall down to the beach, where he was employed in
filling the two watch-glasses with water. I held the wool, while he
lifted the glasses over it; and in a few seconds a hole was burned, and
I observed some sparks travelling round it. I rushed back to the heap
of fuel, blowing as I went; while Halliday stood ready with a leaf of
paper, which he had torn from his pocket-book, and with a heap of
withered twigs and leaves, which with infinite perseverance he had
gathered together. By all of us blowing together a flame was produced,
to our infinite joy. A milky sap, however, came from the shrubs, and
only a small portion of them would ignite, while the