  The third chapter of the Huainanzi ends with a section on the use of the measurements cast by shadows (gnomons) to calculate distances. This passage is probably a later addition, but for our purposes, its inclusion in the Huainanzi is indicative of the scientific concerns of the text. It gives directions for a series of measurements, including how to determine the directions of sunrise, sunset, and the cardinal directions. It also explains how to measure the “breadth and length of east, west, north, and south”: