ANCIENT STONE MONUMENT AT TONGATABU (p. [173]).
On the last day previous to our departure from Tongatabu, we made an excursion to the south side of the island, under the guidance of Mr. Symonds, the British Consul, and Mr. Hanslip, the consular interpreter, in order to examine some caves which were said to be of an unusually wonderful nature. They had, of course, never been thoroughly explored, and were consequently said to be of prodigious extent, forming long tunnels through the island. One story was to the effect that an adventurous woman had penetrated one branch of the cave, entering on the south side of the island, and threading its dark recesses for many days, until she finally emerged into the light of day somewhere near Nukualofa, on the north side of the island.
A pleasant drive of about ten miles brought us to the shore of a small bay exposed to the prevailing wind, and receiving on its beach the full fury of the swell of the main ocean. The foreshore was strewn with coral débris, and above high-water mark were quantities of pumice-stone, probably washed up from the sides of the neighbouring volcanic island of Uea. On either side, the bay was hemmed in by bold projecting crags of coral rock, whose faces indicated, by parallel tide erosions, that they had been elevated by sudden upheaval into their present position. About one hundred yards from the beach, and forty feet above the sea-level, was the entrance to the caves, a narrow aperture in the upraised coral rock, leading by a rapid incline into a spacious vaulted chamber, from whose gloomy recesses dark and forbidding passages led in various directions. In the floor of the chamber were deep pools of water, probably communicating with the sea, and said to be tenanted by a species of blind eel, about two feet long, which we were told the natives sometimes caught with hook and line, and fed upon. I was provided with fishing-tackle for capturing a specimen of this singular creature; but as several of our party were induced to relieve themselves of the intolerable heat of the cave by bathing in these pools, the fish were probably scared away, and I was unable to obtain a single specimen.
The rock pierced by the caverns was everywhere of coral formation, and as water freely penetrated through from the soilcap above, the roof and floor were abundantly decorated with stalactites and stalagmites in all their usual fantastic splendour. I noticed that many parts of the floor of the cave were speckled with white spots resembling bird-droppings, on which drops of water were frequently falling from the roof above, and I formed the opinion that the white colour of these spots was due to the drops of water which pattered on them having traversed a portion of the ground above, from which they did not receive a charge of lime salts, and consequently washing clean the portion of the coral floor on which they fell, instead of depositing thereon a calcareous stalagmite. This surmise was strengthened by observing the absence of stalactites depending from the roof in these situations.
Numbers of small swifts, apparently the same species which is common on the island (Collocalia spodiopygia), flitted about the vaulted parts of the cave, looking in the torchlight like bats, which at first sight I felt sure they must be, until our native guide succeeded in catching one specimen, which resolved our doubts. We traversed the more open parts of the cave to a distance of about one hundred yards from the entrance; but finding further progress all but impracticable, from the narrowness of the passages, and the quantity of water of uncertain depth to be encountered, we soon gave up the attempt, and were glad to return to the cool and clear atmosphere of the upper air.
During the voyage from Tonga to Fiji, we spent a good deal of time in hunting up the reputed positions of certain doubtful "banks," viz., the "Culebras" and "La Rance" banks, with a view to clearing up the question as to their having any real existence except in the too vivid imaginations of the discoverers. On the 24th of November, when in latitude 24° 25′ S., longitude 184° 0′ W., we steamed over the position assigned by the chart to the "La Rance" bank, and here our sounding line ran out to three hundred fathoms without touching bottom, thus sufficiently establishing the non-existence of any such "bank." Our position at this time may be roughly stated as some two hundred miles to the southward of Tongatabu. During the greater portion of the day, the sea-surface exhibited large patches of discoloured water, due to the presence of a fluffy substance of a dull brown colour, which in consistency and general arrangement resembled the vegetable scum commonly seen floating on the stagnant water of ditches. This matter floated on the surface in irregularly-shaped streaky patches, and also in finely-divided particles impregnated the sea-water to a depth of several feet. Samples were obtained by "dipping" with a bucket as well as with the tow-net, and when submitted to microscopic examination it proved to be composed of multitudes of minute confervoid algæ. On slightly agitating the water in a glass jar, the fluffy masses broke up into small particles, which, under a magnifying power of sixty diameters, were seen to be composed of spindle-shaped bundles of filaments. Under a power of five hundred diameters, these filaments were further resolved into straight or slightly-curved rods, articulated but not branching, and divided by transverse septa into cylindrical cells, which contained irregularly-shaped masses of granular matter. These rods, which seemed to represent the adult plant, measured 1⁄2000 inch in width. On careful examination of many specimens, some filaments were observed, portions of which seemed to have undergone a sort of varicose enlargement, having a width two or three times that of the normal filaments. These propagating filaments (if I am right in so calling them) were invested by a delicate tubular membrane, and were filled with a granular semi-transparent matter, in which were imbedded a number of discoid bodies which were being discharged one by one from the ruptured extremity of the tube. These bodies measured 1⁄1000 of an inch in diameter: when viewed edgewise they presented a lozenge-shaped appearance, and they were devoid of cilia or striæ. A jar full of the sea-water was put by until the following day, when it was found that the confervoid matter had all risen to the surface, forming a thick scum of a dull green colour, while the underlying water was of a pale purple colour, resembling the tint produced by a weak solution of permanganate of potash.
From the 24th to the 29th of November, during which time the ship traversed a distance of three hundred miles, we were surrounded by these organisms; during the first three days the large patches were frequently in sight, and for the rest of the time the sea presented a dusty appearance, from the presence of finely-divided particles. On the evening of the 25th an unusually dense patch was sighted, and mistaken for a reef, being reported as such by the look-out man aloft.
On the 28th November I encountered among the proceeds of the tow-net another minute alga, of quite a different appearance from that just described. It was composed of vermiform rods 1⁄1000 inch in width, and breaking up into cylindrical segments with biconcave ends.
We returned to Levuka on the 4th of December, and stayed in harbour for ten days. At this time we had dismal wet weather, and consequently little was done in the way of exploration. I received a visit from a Mr. Boyd of Waidou, a colonist, who has resided for the last sixteen years in Fiji, and who has spent a great deal of his time in collecting natural history specimens. He very kindly presented me with some crania, three of natives of Mallicollo, New Hebrides, and two from Merilava in Bank's Group.
We anchored at Suva for part of a day, in order to fill up with coal, and then proceeded on our voyage to Sydney.