Our earth turns once on its axis in ---- but
before reading on, try to complete this sentence for yourself. Every
one knows that the earth's turning on its axis produces day and night,
and nine persons out of ten, if asked how long the earth takes in
turning round her axis, will answer, 24 hours; and if asked how many
times she turns on her axis in a year, will say 365 times, or if
disposed to be very exact, "about 365-1/4 times." But neither answer
is correct. The earth turns on her axis about 366-1/4 times in each
year, and each turning occupies 23 hours 56 minutes and 4 seconds and
1 tenth of a second. We, taking the ordinary day as the time of a
turning or rotation, lose count of one rotation each year. It is
necessary to mention this, in order that when I tell you how long the
day of Mars is, you may be able correctly to compare it with our own
day. Mars, then, turns on his axis in 24 hours 37 minutes 22 seconds
and 7 tenth-parts of a second. So that Mars requires 41 minutes 18
seconds and 6-tenths of a second longer to turn his small body once
round than our earth requires to turn round her much larger body.
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