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PEBSIAN GULF 196 PERSPECTOGRAPH PERSIAN GULF, an arm of the In- dian Ocean which penetrates between Arabia and Persia to the extent of 650 miles in a general N. W. direction. Its breadth varies from 55 miles at the mouth to 250 miles, and the area is esti- mated at 77,450 square miles, not includ- ing the islands, which are scattered over the W. half, or lie close inshore along the E. side. The chief of these islands are Ormuz, at the mouth; Kishm, 810 square miles in extent ; and the Bahrein Islands. The Great Pearl Bank stretches along the W. side from Ras Hassan to nearly half way up the gulf. The coast is mostly formed of calcareous rocks. With the exception of the Shat-el-Arab, the Persian Gulf receives only insignifi- cant streams. Its E. side presents abundance of good anchorage, either in the numerous bays or in the lee of is- lands. The greater portion of its S. shores now belongs to the Imam of Mus- cat, while the whole of the N. shore be- longs to Persia. The order of the peri- odic currents in this gulf is precisely the reverse of that of the Red Sea currents, as they ascend, from May to October, and descend from October to May. The greatest depth does not exceed 50 fathoms. The submarine telegraph cables be- longing to the government of India, and forming part of the system of the Indo- European Telegraph, pass through the whole length of the Persian Gulf. The pearl fisheries employed before the World War 70,000 men and 6,000 barks. PERSIAN POWDER, a preparation made from the flowers of Pyrethrum corneum or roseuni, and reduced to the form of powder. It is used as an in- secticide. PERSIMMON, or PERSIMON, Dios- pyros virginiana, a tree 60 feet or more in height, with ovate, oblong, taper- pointed, shining leaves, pale yellow flow- ers, and^ an orange-colored succulent fruit an inch or more in diameter; very astringent when green, but eatable when bletted. It grows plentifully in the Southern and South Atlantic States. The fruit is brewed into beer, and yields an ardent spirit on distillation. PERSONAL EQUATION, the correc- tion of personal differences between particular individuals as to exactness in observations with astronomical instru- ments. PERSONALTY, or PERSONAL PROPERTY, movables; chattels; things belonging to the person, as money, jewels, furniture, etc., as distinguished from real estate in lands and houses. PERSONIFICATION, the act of per- sonifying, an embodiment, an impersona- tion. In rhetoric, a figure of speech, or a species of metaj)hor which consists in representing inanimate objects or ab- stract notions as endued with life and action, or possessing the attributes of living beings; prosopopoeia; as, "Confu- sion heard his voice." PERSPECTIVE, the science of repre senting appearances, and as such is op- posed to geometry, which is the science of representing facts. It is founded up- on such rules as can be deduced from the facts which are discovered by looking at objects through a sheet of glass or other transparent medium placed upright be- tween the object and the observer. It is found when objects are so looked at that their apparent form is very different from their real one, both as regards shape and distinctness. The portion of the subject which deals with the changes in form is absolutely scientific; it is called linear perspective. The changes in distinctness are effected by distance and atmosphere, and differ constantly with different conditions of light and at- mosphere. It is the purely artistic side of the science which is called aerial per- spective, and success in its application depends on the individual ability of the artist. The chief point with which linear perspective has to deal is the apparent diminution in size of objects as they re- cede from the spectator. A practical knowledge of the science is absolutely a necessity for a successful artist. A kind of painting designed expressly to deceive the sight by representing the continuation of an alley, a building, a landscape, or the like. Oblique (or angular) perspective, where the plane of the picture is supposed to be at an angle to the side of the principal object in the picture, as, for instance, a building. Parallel perspective, where the plane of the picture is parallel to the side of the principal object in the picture. Perspec- tive plane, the surface on which the ob- jects are delineated, or the picture drawn. It is supposed to be placed vertically be- tween the eye of the spectator and the ob- ject. Also termed the plane of projec- tion, or the plane of the picture. PERSPECTOGRAPH, an instrument for the mechanical drawing of objects in perspective. The object is placed in front of the eye, which is applied to a small hole. A movable hinged bar is so adjusted as to bring a point between the eye and a certain part of the object. The bar is then folded down and the mark transferred to the paper. A series of such marks affords data for the draw- ing of the object.