"We shall get it all right," Mr. Wolston added reassuringly, "by means of this system of irrigation, which I will study if you like."
Jack held his tongue and did not give in. It was by no means an agreeable idea to him that the English colony would some day number a considerable population, and if Mme. Zermatt's inmost heart could have been read the same regret at the thought of the future might have been found there.
However this may be, in the few hours of leisure left to them occasionally by their work in the fields, Mr. Wolston, M. Zermatt and Ernest, who found this kind of task most interesting, studied the question of irrigation. They ascertained accurately the line and level of the country, and were convinced that its disposition was favourable to the construction of a canal.
Rather more than half-a-mile to the south of Wood Grange lay Swan Lake, filled by the rains during the rainy season, but attaining during the dry season a low water mark which rendered it useless. The trenches that might have been cut would not have enabled the water at summer level to drain away. But if they succeeded in keeping a constant surplusage in the lake, by drawing upon Jackal River, it would be easy to divert it over the surrounding land and bring fresh elements of fertility to it by a carefully considered system of irrigation.
The distance between the waterfall and the southern extremity of the lake was a good two and a half miles, it is true, and to build a conduit of that length could not fail to be a task of much magnitude. It would necessitate the felling of a great many sago-trees.
Happily, another examination of the ground, carried out by Ernest and Mr. Wolston, demonstrated the fact that the length of the conduit could be materially reduced.
One evening, when the two families were sitting together in the common hall after a busy day both in and out of doors, Ernest said:
"Papa, Mr. Wolston and I have found out all about the levels. If we raise the water from Jackal River thirty feet, that will be enough to carry it four hundred yards to the place where the ground begins to slope again down to Swan Lake. A trench cut from that point will serve as a canal for the water and will take it direct into the lake."
"Good!" said M. Zermatt. "That will simplify the task enormously."
"And then Swan Lake will form the reservoir for irrigating the fields at Wood Grange, Sugar-cane Grove, and even the hermitage," Mr. Wolston added. "Besides, we will only supply it with enough water for the actual requirements of the irrigation system, and if a surplusage should accumulate we could easily drain it off towards the sea."