Parallel with reading Needham and Lockyer I am documenting the texts of Small Santiago (and London Tablet). There I find what possibly is a glyph (Gb2-21) indicating the breasts of 'mother':

The nipples are seen and below the two breasts appear what may be marks of feathers (implying both sky and brightness). Such a nipple is the apex of the breast (like the top of a hill). The glyph above then could depict two hills, which presumably means two solstices. (Cfr GD33.) We can count the 'feathers' and on the bottom breast there are 6, on the top one 5. Turning the glyph 90 degrees counterclockwise to see the breast in a more normal orientation we have 6 (even number) to the right and 5 (odd number) to the left.

I guess this pattern could mean that the bottom (right) breast is the half-year from winter solstice to summer solstice (yang) and the top (left) breast is the half-year from summer solstice to winter solstice (yin). 6 indicates sun and 5 indicates darkness, i.e. from summer solstice onwards shadows are advancing. The apex in GD33 might illustrate the top of the winter solstice hill = the hill which shadows the sun. In the glyph above we might have this winter solstice hill in the middle, at left (the half-year before) the period from summer solstice to winter solstice and at right (the coming half-year) the period form winter solstice to summer solstice. But then these nipples would show equinoxes.