Tri-an′gu-lar Lev′el.
A light frame in the shape of the letter A, and having a plumb line which determines verticality. It is used in leveling for drains. One leg being placed on a peg driven flush with the surface of the soil, the other leg is brought round till it touches the surface in another place; here another peg is driven. The inclination, say half an inch in the span of the frame, being determined, a peg is driven at the second station half an inch below the level at that point. This gives another point of departure, and the process is a repetition of the former procedure.| Triangular level. |

