"Is it a freshwater lake?" asked Pencroft.
"Certainly," replied the engineer, "for it must be fed by the water which flows from the mountain."
"I see a little river which runs into it," said Herbert, pointing out a narrow stream, which evidently took its source somewhere in the west.
"Yes," said Harding; "and since this stream feeds the lake, most probably on the side near the sea there is an outlet by which the surplus water escapes. We shall see that on our return."
This little winding watercourse and the river already mentioned constituted the water-system, at least such as it was displayed to the eyes of the explorers. However, it was possible that under the masses of trees which covered two-thirds of the island, forming an immense forest, other rivers ran towards the sea. It might even be inferred that such was the case, so rich did this region appear in the most magnificent specimens of the flora of the temperate zones. There was no indication of running water in the north, though perhaps there might be stagnant water among the marshes in the northeast; but that was all, in addition to the downs, sand, and aridity which contrasted so strongly with the luxuriant vegetation of the rest of the island.
The volcano did not occupy the central part; it rose, on the contrary, in the northwestern region, and seemed to mark the boundary of the two zones. At the southwest, at the south, and the southeast, the first part of the spurs were hidden under masses of verdure. At the north, on the contrary, one could follow their ramifications, which died away on the sandy plains. It was on this side that, at the time when the mountain was in a state of eruption, the discharge had worn away a passage, and a large heap of lava had spread to the narrow jaw which formed the northeastern gulf.
Cyrus Harding and his companions remained an hour at the top of the mountain. The island was displayed under their eyes, like a plan in relief with different tints, green for the forests, yellow for the sand, blue for the water. They viewed it in its tout-ensemble, nothing remained concealed but the ground hidden by verdure, the hollows of the valleys, and the interior of the volcanic chasms.
One important question remained to be solved, and the answer would have a great effect upon the future of the castaways.
Was the island inhabited?
It was the reporter who put this question, to which after the close examination they had just made, the answer seemed to be in the negative.
Nowhere could the work of a human hand be perceived. Not a group of huts, not a solitary cabin, not a fishery on the shore. No smoke curling in the air betrayed the presence of man. It is true, a distance of nearly thirty miles separated the observers from the extreme points, that is, of the tail which extended to the southwest, and it would have been difficult, even to Pencroft's eyes, to discover a habitation there. Neither could the curtain of verdure, which covered three-quarters of the island, be raised to see if it did not shelter some straggling village. But in general the islanders live on the shores of the narrow spaces which emerge above the waters of the Pacific, and this shore appeared to be an absolute desert.
Until a more complete exploration, it might be admitted that the island was uninhabited. But was it frequented, at least occasionally, by the natives of neighboring islands? It was difficult to reply to this question. No land appeared within a radius of fifty miles. But fifty miles could be easily crossed, either by Malay proas or by the large Polynesian canoes. Everything depended on the position of the island, of its isolation in the Pacific, or of its proximity to archipelagoes. Would Cyrus Harding be able to find out their latitude and longitude without instruments? It would be difficult. Since he was in doubt, it was best to take precautions against a possible descent of neighboring natives.
The exploration of the island was finished, its shape determined, its features made out, its extent calculated, the water and mountain systems ascertained.