Keeping time

To connect memory to time, the thirteen consonants of the Tree Alphabet correspond to thirteen lunar periods in a year, following an anti-clockwise direction, known as a sidereal clock. Beginning at 'B' each period contains 28 days, giving a total of 364 days in the year (leaving the 'and a day' found in many an old tale!)

Points in time

The five vowels beginning with 'A' follow a solar (sun-wise) direction, tracking solstice and equinox points. Two of them define midwinter, which might seem puzzling until it is seen that they start and end any single year (perhaps difficult to envisage in 2D!)

The nineteenth letter

One further letter 'Q' tracks the nineteen year Metonic cycle, when solar and lunar cycles re-calibrate and at Calanais (Callanish, or Turusachan) is a 5,000 years old computer whose legendary purpose is hinted at by the greek writer, Diodorus, in 55BC:
"..there is also on the isand... a notable temple which is... spherical in shape... the moon, as viewed from this island, appears but a little distance from the earth... the god visits the island every nineteen years..."

The following is taken from geo.org/callan.htm where photographs and fuller detail can be seen. It is repeated here only in case the original source disappears!

Margaret R. Curtis, expert and tour guide of the Callanish area, recounts her experience of this amazing phenomenon. "We saw this rare and spectacular event in June 1987 with friends from across the world. None of us will ever forget the beauty of that calm, clear summer night. Even after years of scientific study, we had never anticipated the wonder and drama of the event itself. The most awe-inspiring moment of all was when the moon reappeared inside the circle."
"For three minutes, never revealing more than half of its orb in the narrow gap. The moon was captured in an artificial frame of megaliths, and the cold gray pillars of stone were bathed in a golden glow.
"Like a lighthouse beam, the moonlight stretched down along the avenue towards us and caught us in its light. Next, a tiny human figure appeared, fitting inside the honey colored moon, then gradually grew, shattering one's sense of scale, until twice the size of the moon. Then the moon vanished and left the person majestic and alone inside the darkened circle.
"Was this the new-born moon god inside the sacred ring of stones reappearing as in prehistoric times, mixing reality and illusion when the person may have been an actor or actress, or a member of the elite, passing on the leadership to a new office bearer? Was this the origin of the legend of 'The Shining One' walking up the avenue?"