**1. The Defacto 13 year Lunar
tidal cycle**

There is a defacto 13 year lunar
tidal cycle created by the difference

between 31 perigee/syzygy cycle and the
18 year Saros cycle, such that:

**13 years = 31 – 18
years**

Now the reason for
the 18.03 sidereal year Saros cycle is:

223 Synodic
months______= 18.02931 sidereal years

239 anomalistic
months___ = 18.02990 sidereal years

242 Draconic
months______= 18.02941 sidereal years

[with closest
alignment between Synodic and Draconic cycles,

though the
anomalistic cycle is not far off]

while the reason for
the 31 year cycle is:

383.5 Synodic
months______= 31.005568 sidereal years

411.0 anomalistic
months___ = 31.005401 sidereal years

416.0 Draconic
months_____= 30.992708 sidereal years

[with closest
alignment between Synodic and anomalistic cycles]

hence, the defacto
13 year cycle possibly comes about because:

160.5 Synodic
months______= 12.976254 sidereal years

172.0 anomalistic
months___= 12.9754963 sidereal years

174.0 Draconic
months_____= 12.9632963 sidereal years

[with closest alignment
between Synodic and anomalistic cycles]

**2.
The 208 year de Vries Cycle**

Now

**16 x 13 years = 208 years**

Thus, this would indicate that a possible
reason for the ~ 208 de Vries cycle is:

16 x 160.5 = 2568.0 Synodic
cycles________= 207.6200718 sidereal years

16 x 172.0 = 2752.0 anomalistic cycles_____= 207.6079414 sidereal years

16 x 174.0 = 2784.0 Draconic cycles_______= 207.4127406 sidereal years
or with a drift of 3.0 Draconic cycles in roughly 208 years you get:

2787.0 Draconic cycles___= 207.6362457 sidereal years

[with closest alignment between Synodic
and anomalistic cycles]

Finally, if you allow for a slight drift
of 4.5 Synodic cycles and 5.0 anomalistic and

Draconic cycles you get:

2572.5 Synodic cycles___= 207.98389
sidereal yrs_____= 207.99196 tropical yrs

2757.0 anomalistic cycles_= 207.98514 sidereal yrs____= 207.99321 tropical yrs

2792.0 Draconic cycles___= 208.00875 sidereal yrs____= 208.01682 tropical yrs

Of course, the drift required to realign
the sidereal/tropical reference frame

with the seasonal year of 4.5 synodic = 5.0 anomalistic = 5.0
Draconic cycles

over 208 tropical years is not arbitrary since this is equivalent
to:

132.887 days in 75970.375 days = 0.0017492
of a full cycle in 208 tropical years.

which for the Earth’s orbit is 0.6297133
degrees in 208.0 tropical years

or 10.90 ~ 11 arc second per tropical year!

This is just the (pro-grade) rate of
precession of the perihelion of the Earth’s orbit

which is
currently about:

11.45 arc seconds per year – theoretical

11.62 arc seconds per year – observed epoch 2000.

**CONCLUSION **

**Hence, If we look at times where the perigee of the lunar orbit
points at the **

**Sun, they will realign with the seasons in (almost) precisely 208.0 tropical **

**years or one de Vries Cycle, if you measure the alignment in a
reference **

**frame that is fixed with the Earth’s orbit (i.e. a frame that is
tracking the **

**perihelion precession of the Earth’s orbit).**