Joseph Smith said that Figure 6 of Facsimile 2 in the Book of Abraham: Represents this earth in its four quarters. Figure 6 contains 4 images which represent the four sons of the god Horus.
Richard H. Wilkinson remarks how they indeed represent the four directions:
The earliest reference to these four gods is found in the Pyramid Texts [ca. 2350–2100 BC] where they are said to be the children and also the “souls” of [the god] Horus. They are also called the “friends of the king” and assist the deceased monarch in ascending into the sky (PT 1278–79). The same gods were also known as the sons of Osiris and were later said to be members of the group called “the seven blessed ones” whose job was to protect the netherworld god’s coffin. Their afterlife mythology led to important roles in the funerary assemblage, particularly in association with the containers now traditionally called canopic jars in which the internal organs of the deceased were preserved. . . . The group may have been based on the symbolic completeness of the number four alone, but they are often given geographic associations and hence became a kind of “regional” group. . . . The four gods were sometimes depicted on the sides of the canopic chest and had specific symbolic orientations, with Imsety usually being aligned with the south, Hapy with the north, Duamutef with the east and Qebehsenuef with the west.– Richard H. Wilkinson, The Complete Gods and Goddesses of Ancient Egypt (London: Thames and Hudson, 2003), 88.
How would Joseph Smith know this interpretation?