that part of grammar which teaches the nature and affections of letters, and the just method of spelling or writing words, with all the proper and necessary letters. It forms one of the four great divisions or branches of grammar.

ORTHOGRAPHY, in Geometry, the art of drawing or delineating the fore-right plan of any object, and of express- ing the heights or elevations of each part. It is called orthography, from its determining things by perpendicular lines falling on the geometrical plane.

Orthography, in Architecture, is the elevation of a building or edifice.

Orthography, in Perspective, is the fore-right side of any plane, that is, the side or plane which lies parallel to a straight line, that may be imagined to pass through the outward convex points of the eyes, continued to a convenient length.

Orthopnea, a species or degree of asthma, where there is such a difficulty of respiration that the patient is obliged either to sit or stand upright in order to be able to breathe.

Orthosa, or Ortozo, a small seaport of Syria, in the pachalik of Tripoli, on the coast of the Mediterranean, about twelve miles north of Tripoli.