trigon2+ (trigon)

[Also trigen; appar. for * triggin, a dial. form of #trigging, And stoppeth the wheel with a Trigen [Sufflamine) in a steep descent. Hoole, tr. of The Visible World, lxxxvi. Trigon, a Pole to stop the Wheel of a Cart, where it goes too fast down a steep Place. Bailey , 1731. trigonal (trig'ō-nal), a . and n. [ entom ., triangular in cro -section; having three long edges; trihedral; prismatic: as, trigonal antennæ; trigonal joints.-3. In bot . , same as trigo nous .-4. In an at . , noting a triangular space at the base of the bladder. See trigonum ( a ). -Trigonal coördinate, one of a set of three coördinates of a point in a plane, which are related to trilinear coördinates as follows. Let zn +1=yn/zu, y+2n / zu, Zn+1=Xn/yn, and let xo, Yo, zo be trilinear coördinates. Then Xn, yn, zn are called trigonal coördinates of the nth cla . Trigonal coördinates are subject to the equation In yn Zn =1, which does not vary with the triangle of reference. They are valuable for studying higher plane curves. Thus, a linear equation in trigonal coördinates of the first cla represents a cubic. They were invented by S. Levi in 1876, and must not be confounded with Walton's trigonic coördinates. - Trigonal residue. See residue. Trigonal trapezohedron. See tetartohedrism. - Trigonal trisoctahedron. See trisoctahedron. II. n. In an at . , the triangular space at the base of the bladder; the trigonum. Trigon a lidæ (trig-ō-nal'i-dē), n. pl. [NL., wood, 1835), block into which the metope was slid. sive block incised with two entire vertical grooves cut to a right angle, called glyphs, framed between three fillets, and with a semi-groove at each side. The block is grooved on both sides to receive the adjoining metopes, which are thin slabs slid into their places from above. The triglyphs represent the ends of the ceiling-beams of the primitive wooden construction. In Greek use terior triglyphs of a range are always slightly displaced, so as to occupy the angles of the frieze instead of coming, like the others, over the centers of the columns; in Roman and affiliated architectures this refinement does not occur; and in Roman and even some of the later Greek examples the triglyphs are merely carved in relief in the face of the frieze-blocks, instead of being, as properly, independent blocks. See also cuts under entablature and mono triglyph. All round between the triglyphs in the frieze there are most exquisite alt-reliefs of combats with centaurs, lions, and many on horses. Pococke , Description of the East, II. ii. 163. triglyphal (tri'glif-al), a. [ tures.