arry.

John smiled, as he replied: "I do not know; the calculations have not
yet been made."

"I would like to know how our position can be found out from an
examination of the sun," remarked George.

"That will require a long answer to explain fully but I shall try to
answer it in a simple manner. The sailor takes an observation of the sun
in two directions, namely, north and south, and east and west. You know,
of course, that the sun moves north in the summer and south in the
winter, and that the extreme southern point is in midwinter, Dec. 20:
that in the spring, or March 20, it is directly above the equator, and
in midsummer, or, on June 20, it is as far north as it can go."

"You mean," said George, "that it would be north of the equator."

"As we have the same calendar over the entire world, it is true
everywhere. The difference is, of course, that summer and winter, and
spring and autumn are reversed, north and south of the equator. All
estimates as to locations are made by measuring angles."

[Illustration: _Fig. 15. Getting Angle from Position of the Sun._]

"Then it must be something like surveying?"

"Yes; the same principles are applied. Here is a sketch, which shows the
earth A, and B is the equatorial line. C is the position of the sun on
September 20, or on June 20."

"Why are they in the same position on both days?"

"Yes; the sun crosses the equator September 20, on its way south, and
then it again recrosses the equator coming north six months afterwards.
On either of those days, if a person should stand at D, and look at the
sun, there would be a line E, which projects out from the earth to the
sun, and that is called the equatorial line."

"It is exactly at right angles to F, which passes through the poles. Now
the drawing shows two other positions, namely G and H. These represent
the extreme points of the travel of the sun north and south, or the
positions that the sun occupy on Dec. 20, and June 20 of each year."

"I see," said Harry. "The points G and H are just 23 degrees north and
south of the equator."

"That is correct, and there is another thing which can be learned from
their positions."

"I know what it is."

"What?"

"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 wi