A beam across an auspicious bearing
Geng is a heavenly stem, element metal, in the Dui trigram with Shen on its left at 240, where Tianguan the Gate sits, and You on its right at 270, where Shaowei, one of the four noble stars, sits. Its opposite is Jia at 75. The three auspicious mountains, Hai at 330, Zhen at 90 and Geng at 255, are prized for sand hills and incoming water, not for the facing. Keep the rank with the mountain and the image with the star. The beam is horizontal: a level ridge, a long low hill that lies across the view and ties the two sides together, a hill that takes weight rather than rising to a point.
How we match the beam to the form
Our practice is to finish with the star ring, not start with it. Lai Buyi's Cui Guan Pian goes dragon, hollow, sand and water, each chapter answered by a star, and in the field that is the sequence. On Geng the usual case is sand: a guarding ridge or a facing hill that reads on 255. If it lies level and whole, joining the left and right arms of the site, the star reads Tianheng, the beam image is apt, and the auspicious bearing is already a point in its favour. Water from Geng is treated the same way. If the ridge on Geng is cut by a road or broken into knobs, the beam is not there, the rank does not restore it, and the star says only that the structure failed.
What this means on the ground
Sight from the site. Grave: stand behind the headstone, read along its face, then turn to the ridge on the right hand side of a south facing stone, which is where Geng usually falls. House or shop: stand inside the main door, back to it, and look out. Level the plate, wait for the needle, three readings, no steel. A reading between 247.5 and 262.5 is Geng, and the star ring slot above it is Tianheng. Note the edges: at 248 the hill is almost on Shen, at 262 almost on You, and a stone or door on either line is straddling and should be shifted inward. In town, a long even block with a level roof line on this bearing is the beam; a gap tooth skyline is not.
Common mistakes
Confusing the Beam with the Constant; same pinyin, different character, 255 against 210. Letting the three auspicious rank carry a broken hill; the rank describes a good peak, it does not create one. Reading the star ring from a phone app, which has no such ring and tends to true north, so that Geng drifts onto Shen or You overseas. Counting stars before the dragon has been walked. Taking the bearing off a satellite image rather than from the stone or the door.
Questions people ask
What star is on Geng mountain?
Tianheng, Heaven's Beam, over 247.5 to 262.5 degrees, west south west. An ordinary star. Geng itself is one of the three auspicious mountains, so a good peak there is valued.
Is Geng one of the three auspicious mountains?
Yes. The three are Hai at 330, Zhen or Mao at 90, and Geng at 255. The rank applies to guarding hills and incoming water on those bearings.
What does Heaven's Beam mean in feng shui?
A cross beam: structure, the meeting of parts, bearing weight. On a hillside it is the image for a level ridge that ties the site together. It describes form and forecasts nothing.
Let Master Zhang read the ridge on your right hand side, or join a Ganzhou field course and learn to tell a beam from a broken line.