The snake branch, and the facing of a Hai seat
A master usually meets Si from the other end of its axis. Hai is noble and auspicious, and a Hai dragon that settles is usually given the seat Hai, facing Si. So what stands on Si is what that grave looks at: the table hill, the water passing across, the far peaks.
Si as a seat is the reverse, back on 150 and face on 330, and rarer, since it puts the noble end of the axis in front. Si as an incoming dragon is a ridge from the south-southeast, read by spine and turn like any other. Fire matters for one thing: a sharp red peak on Si is fire on fire, and the trade likes it low.
Heaven's Screen: a star named for what stands in front
Si carries Tianping, Heaven's Screen. A ping is the folding screen in a hall: it shelters, hides, keeps the wind off. It is a common star.
At Si the school looks at the star mostly from across the axis, because what a Hai grave needs in front is exactly a screen: a low, broad, level-topped hill on Si, near but not high. When the table hill has that shape, Heaven's Screen on the dial confirms it. When Si has instead a gap, a road running straight out, or a tall hill looming, the star is still Heaven's Screen and there is still no screen.
What this means on the ground
To check a Hai grave, stand behind the stone and read along its face, which should fall between 142.5 and 157.5. Then look up: what is on Si? A house facing Si is read from inside the door, back to it; a door reading 150 sits on Hai.
Inside the mountain, 150 is the clean figure. A face toward 143 leans on Xun, the same trigram, a mild lean. A face toward 157 leans on Bing, which is Li, and 157.5 is a trigram line as well, so that lean is taken out before cutting. Three readings, luopan level, no steel in reach, phone set to magnetic north.
Common mistakes
Reading the facing as if it were the seat. Many people measure a Hai grave, see 150, and write Si as its mountain; it sits on Hai and faces Si. Taking the fire of Si into the house as red paint and objects, as if a wall colour had anything to do with a mountain on the luopan.
Setting a stone on 157 because it is still Si, with a trigram line half a degree away. Measuring with true north, which in much of the world moves Si into Xun or Bing. And treating Heaven's Screen as shelter in itself: it names what a good table hill does, and only the hill can do it.
Questions people ask
What direction is Si on a feng shui compass?
Si is south-southeast, 142.5 to 157.5 degrees on the luopan with 150 in the middle. Xun lies on its north side and Bing on its south. It is a fire branch, the snake, the hours of 9 to 11.
What does Hai sitting Si facing mean?
The back of the stone is on Hai, 330 degrees, and the face looks to Si, 150. It is the usual way to set a grave on a Hai dragon, and what stands on Si is then the grave's view.
What kind of hill should be on Si?
For a Hai grave, a low, broad hill with a level top, like a screen before a seat, close but not high. The star on Si is Heaven's Screen, and that shape is the match. A gap or a straight road on Si is the opposite.
For a Hai grave with questions about its table hill, send three readings and a photo from behind the stone and ask for a site reading.