The vessel in the meantime was put under sail and[p. 79] anchored a mile below, giving the surveying party time to make several triangulations, and late in the afternoon the party came on board, tired and ready to take a rest.
From the position taken up by the ship they could see a long stretch of shore line, practically straight, trending toward the southeast, and with their glass could see, miles away, a headland which afforded a pronounced point for observation.
The next morning the same parties rowed to the shore, and Uraso was left with the party to guard the shore boat, while Muro accompanied John and the boys. On this occasion John issued the following instruction:
"The long point which you see in the distance is, probably, 15 miles beyond. It is not more than that, but this clear atmosphere is liable to deceive. I have instructed Sutoto to wait until one o'clock today, and if by that time there is no word from us Uraso will return to the ship, and you will take up anchor and steer for the headland beyond."
"So that you may understand our movements, we will strike into the interior, taking a course due east, for ten miles, or thereabout, and then turn to the south, and reach the sea near the place where the vessel will be located."
"I understand, now, how the distance can be measured by triangulation on land; but how to get the distances, on shipboard, is what puzzles me," said Harry.
John smiled as he replied: "I knew you would[p. 80] come to that sooner or later, so I prepared a little sketch ([Fig. 7]), which shows the bow of a vessel, and the tall mast. The lines from A to B give an angle with the vertical line of the mast, which will enable you to determine how far the ship is from any point."
"But I am still in the dark as to how, even if we have that distance, we can thereby tell by triangulation, on the vessel, how far one point is from another on the land."
