From the Custom House returns it is impossible to form any calculation as to the value of the precious stones exported from the island. A portion only appears, even of those sent to England, the remainder being carried away by private parties. Of the total number found, one-fourth is probably purchased by the natives themselves, more than one-half is sent to the Continent of India, and the remainder represents the export to Europe. Computed in this way, the quantity of precious stones found in the island may be estimated at 10,000l. per annum.
RIVERS.—From the mountainous configuration of the country and the abundance of the rains, the rivers are large and numerous in the south of the island—ten of considerable magnitude flowing into the sea on the west coast, between Point-de-Galle and Manaar, and a still greater number, though inferior in volume, on the east. In the low country, where the heat is intense and evaporation proportionate, they derive little of their supply from springs; and the passing showers which fall scarcely more than replace the moisture drawn by the sun from the parched and thirsty soil.
Hence in the plains there are comparatively few rivulets or running streams; the rivers there flow in almost solitary lines to the sea; and the beds of their minor affluents serve only to conduct to them the torrents which descend at the change of each monsoon, their channels at other times being exhausted and dry. But in their course through the hills, and the broken ground at their base, they are supplied by numerous feeders, which convey to them the frequent showers that fall in high altitudes. Hence their tracks are through some of the noblest scenery in the world; rushing through ravines and glens, and falling over precipitous rocks in the depths of wooded valleys, they exhibit a succession of rapids, cataracts, and torrents, unsurpassed in magnificence and beauty. On reaching the plains, the boldness of their march and the graceful outline of their sweep are indicative of the little obstruction opposed by the sandy and porous soil through which they flow. Throughout their entire course dense forests shade their banks, and, as they approach the sea, tamarisks and over-arching mangroves mark where their waters mingle with the tide.
Of all the Ceylon rivers, the most important by far is the Mahawelli-ganga—the Ganges of Ptolemy—which, rising in the south near Adam's Peak, traverses more than one-third of the mountain zone[1], drains upwards of four thousand square miles, and flows into the sea by a number of branches, near the noble harbour of Trincomalie. The following table gives a comparative view of the magnitude of the rivers that rise in the hills, and of the extent of the low country traversed by each of them:—
| Embouchure. | Square Miles drained in Mountain Zone. | Square Miles drained in the low Country, about | Length of Course of the main Stream. | |
| Mahawelii-ganga | near Trincomalie | 1782 | 2300 | 134 |
| Kirinde | at Mahagan | 34 | 300 | 62 |
| Wellawey | near Hambangtotte | 263 | 500 | 69 |
| Neivalle | at Matura | 64 | 200 | 42 |
| (Three Rivers) | near Tangalle | 56 | 200 | |
| Gindura | near Galle | 180 | 200 | 59 |
| Kalu-oya | at Caltura | 841 | 300 | 72 |
| Kalany | Colombo | 692 | 200 | 84 |
| The Kaymel or Mahaoya | near Negombo | 253 | 200 | 68 |
| Dederoo-oya | near Chilaw | 38 | 700 | 70 |
| 4212 | 5100 |
1: See ante, [p. 12], for a definition of what constitutes the "mountain zone" of Ceylon.
In addition to these, there are a number of large rivers which belong entirely to the plains in the northern and south-eastern portions of the island, the principal of which are the Arive and the Moderegam, which flow into the Gulf of Manaar; the Kala-oya and the Kanda-lady, which empty themselves into the Bay of Calpentyn; the Maniek or Kattragam, and the Koombookgam, opposite to the Little Bass rocks and the Naveloor, the Chadawak, and Arookgam, south of Batticaloa. The extent of country drained by these latter streams is little short of thirteen thousand square miles.
Very few of the rivers of Ceylon are navigable, and these only by canoes and flat-bottomed paddy boats, which ascend some of the largest for short distances, till impeded by the rapids, occasioned by rocks in the lowest range of the hills. In this way the Niwalle at Matura can be ascended for about fifteen miles, as far as Wellehara; the Kalu-ganga can be traversed from Caltura to Ratnapoora; the Bentotte river for sixteen miles to Pittagalla; and the Kalany from Colombo to the foot of the mountains near Ambogammoa. The Mahawelli-ganga is navigable from Trincomalie to within a short distance of Kanda[1]; and many of the lesser streams, the Kirinde and Wellawey in the south, and the Kaymel, the Dedroo-oya, and the Aripo river on the west of the island, are used for short distances by boats.
1: For an account of the capabilities of the Mahawelli-ganga, as regards navigation, see BROOKE'S Report, Roy. Geog. Journ. vol. iii. p. 223. and post, Vol. II. p. 423.
All these streams are liable, during the fury of the monsoons, to be surcharged with rain till they overflow their banks, and spread in wide inundations over the level country. On the subsidence of these waters, the intense heat of the sun acting on the surface they leave deserted, produces a noxious and fatal malaria. Hence the rivers of Ceylon present the curious anomaly, that whilst the tanks and reservoirs of the interior diffuse a healthful coolness around, the running water of the rivers is prolific of fevers; and in some seasons so deadly is the pestilence that the Malabar coolies, as well as the native peasantry, betake themselves to precipitate flight.[1]