"
"And what is one third of forty-five?"
The boys would readily answer fifteen, and the teacher would then dwell
for a moment on the general truth thus deduced, that the sun, in passing
round the earth, passes over fifteen degrees every hour.
"Suppose, then, it takes the sun one hour to go from us to the River
Mississippi, how many degrees west of us would the river be?"
Having thus familiarized the pupils to the fact that the motion of the
sun is a proper measure of the difference of longitude between two
places, the teacher must dismiss the subject for a day, and when the
next opportunity of bringing it forward occurs, he would, perhaps, take
up the subject of the sun's motion as a measure _of time._
"Is the sun ever exactly over our heads?"
"Is he ever exactly south of us?"
"When he is exactly south of us, or, in other words, exactly opposite to
us in his course round the earth, he is said to be in our meridian; for
the word meridian means a line drawn exactly north or south from any
place."
There is no limit to the simplicity which may be imparted, even to the
most difficult subjects, by subdividing the steps. This point, for
instance, the meaning of meridian, may be the subject, if it were
necessary, of many questions, which would render it simple to the
youngest child. The teacher may point to the various articles in the
room, or buildings, or other objects without, and ask if they are or are
not in his meridian.
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