Before dealing with those of Vanua Levu I will mention the other localities in the group in which thermal springs are from various sources known to me. They probably form but a small proportion of those that actually exist; but the list can be readily extended by those acquainted with special parts of the archipelago. In Viti Levu they occur amongst other places at Wai Mbasanga, on the Singatoka river (Horne) and at Na Seivau on the Wai Ndina, where Macdonald in 1856 found temperatures of 106° and 140° Fahr. in two different springs.[[16]] Mr. Thiele in more recent years referred by hearsay to some hot springs on the Wai Ndina.[[17]] Kleinschmidt in 1876 visited a hot spring near the village of Nambualu in the island of Ono which rose up in the midst of a brook and had a temperature of about 100° Fahr.[[18]] The same naturalist in July of that year, when accompanied by Dr. Max Büchner, came upon a hot spring issuing among the mangroves at the coast about a mile from the village of Ndavingele in Kandavu. He did not take the temperature; but he says that Colonel Smythe (about 1860) observed the temperature to be 144° Fahr.[[19]] Different writers refer to extensive hot springs on the island of Ngau. They are placed near the beach, and close to an ordinary cool spring. Miss Gordon Cumming in At Home in Fiji gives an illustration of them. Horne mentions a hot spring on the island of Rambi. Andrews describes two others that bubble up through the limestone near the tidal zone in the southern part of Vanua Mbalavu. Both these springs are in close proximity to the junction line between the intruded andesite and the old reef rock. One of them, though not boiling, was hot enough to scald the skin.[[20]] This list is no doubt capable of being much extended, especially for Viti Levu and the Lau Group.
A description of the several systems of thermal springs of Vanua Levu will now be given.
1. The Hot Springs of the Lower Valley of the Wainunu River.—This is one of the most extensive systems of the kind in the island. The temperature of the various springs during my sojourn in this district in 1898 ranged from 100° to 130° Fahr. Those known to me are mostly situated in the lower part and at the mouth of the Ndavutu Creek, one of the tributaries of the Wainunu. They open usually on the river-bank, either close to the water or a few feet above it, but some of them find an exit under water at the bottom of the river. Natives allege that hot springs occur at intervals on the left bank and at the river-bottom along the whole length of the river below Ndavutu Creek. There is certainly a hot spring on the right side of the river’s mouth near Mr. Dyer’s house. It issues from the reef-flat and can only be observed at exceptionally low tides. There is also a hot spring which rises up at the edge of the stream at Thongea (Cogea) nearly a mile above Ndavutu. If the above statement of the natives is correct, as I believe it is, then these thermal springs issue along a line quite four geographical miles in length extending inland from the mouth of the Wainunu.
All the springs are situated in the tidal part of the river-valley, with the exception of that of Thongea, which is just above this limit. They are but little elevated above the sea-level, those exposed being usually not more than ten feet above the river and often much less. This is a region of basalt, the valley of the Wainunu lying, as described on page [82], in the fold between two great basaltic flows, and probably representing a line of weakness, along which the hot springs issue either from among loose blocks, or from the soil, or from a tufaceous sandstone. They deposit little if any of the siliceous sinter which is often found in the thermal waters of this island. This is due probably to their scanty exposure and to their low temperature. The density of the water is near that of fresh water, being not over 1001. The following temperatures may be useful for comparison with future observations:
| Thongea, | when not covered by the stream | July, | 1898, | 127° | F. | ||
| Ndavutu, | bath-spring at Mr. Barratt’s house | Usually | 100° | " | |||
| " | on left bank of the creek near the landing place | June, | 1898, | 126° | " | ||
| " | on left bank of creek near mouth | Dec. | " | 127° | " | ||
| " | pool in foot-path on left bank | June 2, | " | 112° | " | ||
| July 27, | " | 111° | " | ||||
| " | at bottom of main river in depth of 3 feet, close to the left bank and just above the mouthof the Ndavutu creek, self-registering Six thermometer used | July | " | 122° | " | ||
2. The Hot Springs of Natoarau and its Vicinity.—This thermal system lies in the lower valley of the Mbale-mbale branch of the river Ndreke-ni-wai. The principal springs are situated at Natoarau, a village about half a mile in a direct line from Mbale-mbale, about three miles from the coast, and only about fifty feet above the sea. They bubble up in pools near brooks, and extend at intervals over an area probably several hundred yards across. Five springs came under my notice; but there are doubtless several others in the low-lying and often swampy land of this district. No deposits were noticed, but the mode of occurrence and low temperature of the springs serve to explain this fact. The following temperature observations were made by me in March, 1899:—
| A. | Pool 4 feet across, with sides of stone, close to village | 126° | F. |
| B. | Pool 10 feet wide, a few paces from pool A | 114° | " |
| C. | Pool 12 feet wide, 100 yards from village, near the river | 103° | " |
| D. | Pool on the road to Mbale-mbale, mixed with surface water | 100° | " |
The natives and others often state that the thermal springs here and in other localities are much hotter in dry than in rainy weather. This is correct in a sense, because in wet weather the surface water would usually find access to the pools; but there is no reason to believe that the temperature of the water at the hole of exit varies at all from this cause. The temperature of pool A was taken at the bottom where the water bubbled up; and probably it represents the true degree of heat of these springs, since in the other cases observation of this point was not so easy. The weather was dry during this visit; but, three months before, I tested the temperature of this pool after heavy rain, when the district was flooded, and then I got a reading of 127° at the exit-hole of the spring.
Another thermal spring, which is distant about a mile from Natoarau, is known as Waitunutunu, that is, Warm Water. It lies about a third of a mile from the village of Nambuniseseri, between Mbale-mbale and Waisali, and is quite four miles inland and about 100 feet above the sea. The springs bubble up into a pool, about 12 feet across, which is close to a brook and had a temperature in March, 1899, of 109-112° F.
3. The Hot Springs of Nukumbolo.—The village of Nukumbolo, where the springs are situated, lies on the banks of a tributary of the Vatu-kawa branch of the river Ndreke-ni-wai, and is distant as the crow flies about six miles inland from the river’s mouth. The springs issue on a hill-slope from several places a few steps apart, and are removed about a hundred yards from the river, and from 20 to 30 feet above it. Their elevation above the sea would be about 130 feet. The temperature taken in the two hottest places was 157° F, in November 1898, and 158° in the following February. As in the case of the springs of Savu-savu and a few other localities, the rocks are coated with siliceous sinter mixed with carbonate of lime, and a gelatinous incrusting alga grows on the borders of tiny hollows bathed often in water of a temperature 137-140°, but thriving most where the temperature is 115-120°. The water runs down the slope into a series of pools made by the natives for bathing, the temperature of the lowest pool being 103-105° and of the highest 120°. This is one of the best localities I have seen in the island for the erection of thermal baths. The rock pierced by the springs is apparently a basic agglomerate-tuff. Large blocks of a hard and somewhat altered palagonitic tuff lie around the bathing pools.