We know the rate at which the earth is spinning, and we have observed the precessional motion.
The effect of its fluctuation is inseparable from the precessional effect, and is related to it as a modifying condition.
The search of the rocks for records of the ticks of the precessional clock is an out-of-door work.
When the eccentricity is large the precessional rhythm is emphasized; when it is small the precessional effect is weak.
So that the precessional motion changes its rate every quarter year from a maximum to nothing, or from nothing to a maximum.
But the precessional motion pulses steadily on through the ages, like the swing of a frictionless pendulum.
If the precessional velocity is too small, the top will fall, and as it falls the precessional velocity increases.
For instance, the precessional motion of a top cannot be reversed unless we reverse the spin.
The precessional movement is represented by a revolution around the pole of the ecliptic, as is shown in the figure.
This fundamental advance rendered inevitable the detection of precessional effects.
1590s, from Late Latin praecissionem (nominative praecissio) "a coming before," from past participle stem of Latin praecedere "to go before" (see precede). Originally used in reference to calculations of the equinoxes, which come slightly earlier each year.