PER 



PER 



posed of one irregular petal, with two 

 lips, resembling 1 the head or snout of an 

 animal. In toad-flax, the petal is termi- 

 nated behind by a nectarium in form of a 

 spur. The stamina in plants of the first 

 section, are two or four in number. . In 

 hedge-hyssop, and some species of ver- 

 vain, the filaments are four in number, but 

 two of these only are terminated by an- 

 thers ; so that the number of perfect sta- 

 mina in these plants is only two. The 

 seed-bud is single, and placed above the 

 receptacle of the flower. The style is 

 single, thread-shaped, bent in the direc- 

 tion of the stamina, and crowned with a 

 stigma, which is generally blunt, and 

 sometimes divided into two. The seed- 

 vessel is a capsule, generally divided in- 

 ternally into two cavities, and externally 

 into the same number of valves. The 

 seeds are numerous, and affixed to a re- 

 ceptacle in the middle of the capsule. 



PEUSOONIA, in botany, so named in 

 honour of C. H Persoon ; a genus of the 

 Tetrandria Monogynia class and order. 

 Essential character : calyx none ; petals 

 four, staminiferous towards the base; 

 glands four at the base of the germ ; stig- 

 ma blunt ; drupe one-seeded. This ge- 

 nus consists of subvimineous shrubs; 

 leaves commonly alternate, without sti- 

 pules ; corolla smooth within : anthers 

 linear, finally bent back; style perma- 

 nent, smooth; drupe eatable in most; 

 flowers yellow. Natives of the islands in 

 the Southern Ocean. 



PERSPECTIVE is the foundation of 

 all the polite or liberal arts that have 

 their basis in drawing; though colouring, 

 taken abstractedly, does not come within 

 its rules, yet the painter, as well as the 

 sculptor and architect, cannot but de- 

 rive essential advantages from a know- 

 ledge of perspective ; it is indeed diffi- 

 cult to conceive how a person, who has 

 not either been instructed in, or been 

 gifted by nature with some idea of the 

 effects produced by locality and distance, 

 can form any thing like a correct opinion 

 of the merits of those imitations of na- 

 ture which come under the heads of por- 

 trait, landscape, figure, or architectural 

 drawing. 



Perspective is, in brief, the art of re- 

 presenting, upon a plane surface, the ap- 

 pearance of objects, however diversified, 

 similar to that they assume upon a glass- 

 plane, interposed between them and the 

 eye at a given distance. The represen- 

 tation of a solid object on a plane surface 

 can shew the original in no other point of 

 view but that from which it is at the time 



beheld by the draughtsman; the least 

 change in any of the parts requires a 

 change in the whole ; unless in fancy 

 drawings, where a fac-simile is not re- 

 quired. Nor can any deviation from the 

 several lines, which will be hereafter ex- 

 plained, and on which the truth and cor- 

 rectness of representation depend, be al- 

 lowed, without changing the bearings, di- 

 rections, and tendency of all the perspec- 

 tive lines, which constitute the basis of 

 that faithful and converging series which 

 unite all the component parts in the most 

 pleasing and harmonious concinnity. 



By perspective we are taught to deli- 

 neate objects on a plane, upon geometri- 

 cal principles, and in exact ratio with 

 their several magnitudes, governed by 

 their distance. But it is not in the power 

 of art to represent any single figure, 

 (exact as it appears in nature), on a 

 plane, except it be a circle ; and then the 

 point of sight, or direct position of the 

 eye, must be perfectly centrical. The 

 reasons for this are obvious ; every ob- 

 ject which recedes from the eye, (such 

 as a row of houses in an oblique direc- 

 tion), inevitably requires that its more 

 remote parts should be represented as 

 being of less magnitude than those more 

 in front, that is, nearer to the spectator. 

 Now, although it is considered an axiom 

 in perspective that all objects standing 

 parallel to the base line, or bottom of the 

 picture, should be represented as pre- 

 serving in every instance the real propor- 

 tions of the scale from which their parts 

 were taken; yet when we analyze the 

 object, according to the various angles 

 those several parts make with the eye, 

 we shall find that even such full pointing 

 figures require their more remote parts 

 to be reduced in proportion as they be- 

 come more distant from the centre, or 

 point of sight. But it will be obvious, 

 that where the object is very remote, 

 there must be the less necessity for such 

 scrupulous attention ; therefore, when we 

 draw an extensive mansion, full fronting, 

 at a great distance, we describe all the 

 horizontal lines in the building by hori- 

 zontal lines in the drawing ; so long as 

 they are comprehended within an angle 

 of 60 degrees ; which is the natural 

 range of sight, and beyond which no pic- 

 ture should ever extend ; when beyond 

 that angle, we cannot take the whole pic- 

 ture at one view ; but must treat it as a 

 panorama, and view the several parts ab- 

 stractedly. When a building is so near 

 as to occasion turning our heads round 

 for the purpose of seeing its several 



