l discharges appeared
to go on principally from the mountain heights on both sides of the
Straits.

I allowed the _Vega_ to remain in the harbour of Point de Galle,
partly to wait for the mail, partly to give Dr. Almquist an
opportunity of collecting lichens on some of the high mountain
summits in the interior of the island, and Dr. Kjellman of examining
its algae, while I myself would have time to visit the famous
gem-diggings of Ceylon. The return was as good as could have been
expected considering our short stay at the place. Dr. Almquist's
collection of lichens from the highest mountain of Ceylon,
Pedrotalagalla, 2,500 metres high, was very large, Kjellman, by the
help of a diver, made a not inconsiderable collection of algae from
the neighbourhood of the harbour, and from an exclusion which I
undertook in company with Mr. ALEXANDER C. DIXON, of Colombo, to
Ratnapoora, the town of gems, where we were received with special
kindness by Mr. COLIN MURRAY, assistant government agent, I brought
home a fine collection of the minerals of Ceylon.

Precious stones occur in Ceylon mainly in sand beds, especially at
places where streams of water have flowed which have rolled,
crumbled down, and washed away a large part of the softer
constituents of the sand, so that a gravel has been left remaining
which contains considerably more of the harder precious stone layer
than the original sandy strata, or the rock from which they
originated. Where this natural washing ends, the gem collector
begins. He searches for a suitable valley, digs down a greater or
less depth from the surface to the layer of clay mixed with coarse
sand resting on the rock, which experience has taught him to contain
gems[388]. At the washings which I saw, the clayey gravel was taken
out of this layer and laid by the side of the hole until three or
four cubic metres of it were collected. It was then carried, in
shallow, bowl-formed baskets from half a metre to a metre in
diameter, to a neighbouring river, where it was washed until all the
clay was carried away from the sand. The gems were then picked out,
a person with a glance of the eye examining the wet surface of the
sand and collecting whatever had more or less appearance of a
precious stone. He then skimmed away with the palm of the hand the
upper stratum of sand, and went on in the same way with that below
it until the whole mass was examined. The certainty with which he
judged in a moment whether th