Since this book appeared in 1915 there have been many new insights and several new finds of old texts. So it is a bit outdated, but still a jewel. I learned a lot from it.
ISBN 486-21321-8, edition published in 1965, 820 pages
Do ghosts leave footprints? Page 367 of Wieger, 'Chinese characters'. The text:
Sometimes the offering is presented to a footprint, or to foot-prints of the deceased Ancestor. Now-a-days, as of old, the Chinese try to discern the foot-prints of the departed, on planks strewn over with sand or ashes. See above four figures showing the worship of foot-prints. In the first and second, there is one; in the third there are two of them. In the fourth, the Ancestor has walked all around the offering, sniffing its smell. In the fifth, the legs of the Ancestor are visible. The frame which encloses three of these Graphies, will be explained on page 368.
Page 368: The temple of the deceased Ancestor, or rather the sacred niche from whence his transcendent influence is supposed to emanate, is figured by a frame, square or rectangular, often with inward curved angles.