"It gives another line, or angle."
"So now we have two angles, this, and the equatorial line. Then, we know the exact distance of the sun from the earth, and this gives the first measurement, and with the angle formed by the line I, taken in connection with the line E, it is easy to determine just where, or how far the sun is to the north or to the south, and if you did not, for instance, know the time of the year, a man could by such a measurement, tell, by the angle thus formed, the exact date."
"I understand that now," remarked George. "The sailor, in getting the angle, simply measures that, and if he knows where the sun is on that day[p. 214] he will then have two angles, one that he knows beforehand, and the other that he finds out by looking at the sun."
"That is correct. The Nautical Chart gives all that information, so that it saves a large amount of work in making the calculations."
"That gives the way to determine positions north and south. But how about east and west?"
"In the same manner exactly so far as the angle measurements are concerned, but in this case, instead of taking the time, in days or in months, as in reckoning north and south, we must take time in minutes, and to do that the entire globe is laid off in minutes and degrees, which the nautical tables give, and the mariner knows when he obtains a certain angle just how far east or west he is located by the chart."
"But if he has no chart?"
"Then he must figure out the position for himself, which he can do if he has what is called Greenwich, or standard time, and has, also the correct time of the day where his ship is."
Land was beyond; there was no question of that. It rose out of the water higher than the island they had just left, which the boys had named Venture Island.
The Chief knew nothing of the land before them. He had told John that years before he learned that there was a land where there were many bad people, who killed and ate each other, but he did not know the exact direction.