Abri Blanchard Calendar: Layout
I have prepared this diagram on the premise that Liú Xiàng's words were an aide memoire for the layout and subsequent interpretation of the almanac. If you imagine the pink line as being perpendicular to the plane marked as the ecliptic, it represents the ecliptic pole. If you imagine it to be on the same plane as the ecliptic, it represents 0° or the vernal equinox.
I doubt if the layout is meant to represent a real epoch, but rather a notional moment in time, from which the almanac user derives several charts for current use.
So how old is the almanac? I thought that it might be interesting to speculate a little about Zhuānxū. The design on the bone seems to be very well thought out. It may therefore be a copy of an older design. The design might resemble the design described by Liú Xiàng. If we assume that the bone was designed by Zhuānxū, and if we also assume that Zhuānxū lived at a time when Yíngshì was at longitude 315° on the ecliptic, we can construct a timeline of possible dates (below).
I have estimated the most recent time at which Yíngshì would have been at longitude 315° as 1201 BCE, and then used a precession period of 25,764 years to estimate the previous points.
It is impossible to know whether there is any connection between the Abri Blanchard diagram and the Zhuānxū calendar. If there were a connection, we would then be left with the issue of chronology. Did Zhuānxū come first or Blanchard, or did they both evolve separately from a common root. My intention here is merely to make other researchers aware of the possible existence of a pattern.
There are still some questions to be answered regarding the bone plaque, for example:
There are notches along three edges of the bone. Do they refer to a diagram on the other side of the bone, or do they represent some kind of scale relating to the image that we see in this article?
Are we meant to shoot the other arrows, and if so what do they reveal?