Page 76 - English
P. 76
XI: Astronomical.
A Sidereal day is the time from the sun leaving the sky till he
appears again.
The farther the sun is up the longer it takes it to set and the days are
longer in summer than when the sun is low down.
The weight of the earth is found by comparing a mass of known lead
with that of a mass of unknown lead.
To find the weight of the earth take the length of a degree on a
meridian and multiply by 62½ pounds.
The size of the earth is found by finding the horizontal-parallax of
the sun.
Abberation is if we saw a star and shot at it, the shot would not pass
through the center but through the side.
The moon is 240 miles from the earth.
The moon’s nodes are the corners of the moon’s orbit.
The reason for believing that there are mountains on the moon is due
to the shadows reflected on the earth.
The libration of the moon show the north, east, south, and west sides
of the heavens.
The motions of the moon are found by watching the sun spots.
74
