"So then," added the engineer, "Prospect Heights will become a regular island, being surrounded with water on all sides, and only communicating with the rest of our domain by the bridge which we are about to throw across the Mercy, the two little bridges already established above and below the fall; and, lastly, two other little bridges which must be constructed, one over the canal which I propose to dig, the other across to the left bank of the Mercy.Now, if these bridges can be raised at will, Prospect Heights will be guarded from any surprise."The bridge was the most urgent work.Trees were selected, cut down, stripped of their branches, and cut into beams, joists, and planks.The end of the bridge which rested on the right bank of the Mercy was to be firm, but the other end on the left bank was to be movable, so that it might be raised by means of a counterpoise, as some canal bridges are managed.
This was certainly a considerable work, and though it was skillfully conducted, it took some time, for the Mercy at this place was eighty feet wide.It was therefore necessary to fix piles in the bed of the river so as to sustain the floor of the bridge and establish a pile-driver to act on the tops of these piles, which would thus form two arches and allow the bridge to support heavy loads.
Happily there was no want of tools with which to shape the wood, nor of iron-work to make it firm, nor of the ingenuity of a man who had a marvelous knowledge of the work, nor lastly, the zeal of his companions, who in seven months had necessarily acquired great skill in the use of their tools; and it must be said that not the least skilful was Gideon Spilett, who in dexterity almost equaled the sailor himself."Who would ever have expected so much from a newspaper man!" thought Pencroft.
The construction of the Mercy bridge lasted three weeks of regular hard work.They even breakfasted on the scene of their labors, and the weather being magnificent, they only returned to Granite House to sleep.
During this period it may be stated that Master Jup grew more accustomed to his new masters, whose movements he always watched with very inquisitive eyes.However, as a precautionary measure, Pencroft did not as yet allow him complete liberty, rightly wishing to wait until the limits of the plateau should be settled by the projected works.Top and Jup were good friends and played willingly together, but Jup did everything solemnly.
On the 20th of November the bridge was finished.The movable part, balanced by the counterpoise, swung easily, and only a slight effort was needed to rise it; between its hinge and the last cross-bar on which it rested when closed, there existed a space of twenty feet, which was sufficiently wide to prevent any animals from crossing.
The settlers now began to talk of fetching the balloon-case, which they were anxious to place in perfect security; but to bring it, it would be necessary to take a cart to Port Balloon, and consequently, necessary to beat a road through the dense forests of the Far West.This would take some time.Also, Neb and Pencroft having gone to examine into the state of things at Port Balloon, and reported that the stock of cloth would suffer no damage in the grotto where it was stored, it was decided that the work at Prospect Heights should not be discontinued.
"That," observed Pencroft, "will enable us to establish our poultry-yard under better conditions, since we need have no fear of visits from foxes nor the attacks of other beasts.""Then," added Neb, "we can clear the plateau, and transplant wild plants to it.""And prepare our second corn-field!" cried the sailor with a triumphant air.
In fact, the first corn-field sown with a single grain had prospered admirably, thanks to Pencroft's care.It had produced the ten ears foretold by the engineer, and each ear containing eighty grains, the colony found itself in possession of eight hundred grains, in six months, which promised a double harvest each year.
These eight hundred grains, except fifty, which were prudently reserved, were to be sown in a new field, but with no less care than was bestowed on the single grain.
The field was prepared, then surrounded with a strong palisade, high and pointed, which quadrupeds would have found difficulty in leaping.As to birds, some scarecrows, due to Pencroft's ingenious brain, were enough to frighten them.The seven hundred and fifty grains deposited in very regular furrows were then left for nature to do the rest.
On the 21st of November, Cyrus Harding began to plan the canal which was to close the plateau on the west, from the south angle of Lake Grant to the angle of the Mercy.There was there two or three feet of vegetable earth, and below that granite.It was therefore necessary to manufacture some more nitro-glycerine, and the nitro-glycerine did its accustomed work.In less than a fortnight a ditch, twelve feet wide and six deep, was dug out in the hard ground of the plateau.A new trench was made by the same means in the rocky border of the lake, forming a small stream, to which they gave the name of Creek Glycerine, and which was thus an affluent of the Mercy.As the engineer had predicted, the level of the lake was lowered, though very slightly.To complete the enclosure the bed of the stream on the beach was considerably enlarged, and the sand supported by means of stakes.
By the end of the first fortnight of December these works were finished, and Prospect Heights--that is to say, a sort of irregular pentagon, having a perimeter of nearly four miles, surrounded by a liquid belt--was completely protected from depredators of every description.
During the month of December, the heat was very great.In spite of it, however, the settlers continued their work, and as they were anxious to possess a poultry-yard they forthwith commenced it.
