409 



PERSICA. 



PERSPECTIVE. 



410 



feet high, is formed of 1 4 courses of large blocks of white marble, each 

 stone being beautifully fitted and clamped to its neighbour, and 

 bevilled at the joints, it is therefore admirable as an example of 

 ancient Persian masonry, but of little architectural value. Other marble 

 platforms occur on which also buildings have once doubtless stood, 

 but of which no vestiges remain. In the plain are a fragment or two 

 of large isolated pillars ; and a curious tower-like structure of white 

 marble 9 feet square, and 49 feet high. This is probably one of the 

 fire-temples of the aucient Persians. A similar building is foitnd at 

 Istakii opposite the tombs of Naksh-i-Rustam. It is of marble ; and 

 the lower part being solid, it is entered by a door some height from 

 the ground. There is a small square upper chamber, the roof of 

 which is formed by large slabs of stone ; and this roof is said to still 

 show marks of fire. 



At Susa, Mr. Loftus discovered, in 1843, the foundations of a 

 temple-palace almost identical in plan with the Great Hall of Xerxes 

 at Persepolis, and which though more ruinous than that building, has 

 served -to complete our knowledge of the portions there wanting. 

 Many fragment^ of 'bases and capitals, Tike those of Persepolis, but 

 rather richer ia detail, were also found among the ruins of Susa. 

 Inscriptions on the bases of the columns record the names of Darius and 

 Xerxes asHhe builders, and Artaxerxes Jlemnon as the restorer of the 

 edifice. Other names also occur. This may have been, as has been 

 suggested, the very hall of Shushan, described in the book of Esther ; 

 and at any rate the account there given (c. i. v. 6) of the splendour of the 

 fittings, the columns of marble, and the coloured marble pavement, on 

 which were beds or thrones of gold and silver, will serve to indicate 

 the magnificence of the hall when in its pristine glory. 



At Naksh-i-Rustam are several tombs and sepulchral chambers 

 hewn out of the perpendicular face of rocks. For the most part these 

 excavations are very shallow, and consist chiefly of an architectural 

 frontispiece or portico richly -adorned with sculpture and other 

 decorations. The most remarkable is the Tomb of Darius, the son of 

 Hystaspes, at the foot of Mount Rachmed, near the river Bendemir, 

 the ancient Araxes. Thia monument has a portico of four columns, 

 whose capitals have figures of the foreparts of animalsj>rojecting from 

 their sides. There are also two rows of sculpture above the portico, 

 with a figure of the king above standing opposite a fire-altar, and over 

 all a winged deity is seen floating in the air. As already mentioned, 

 the whole frontispiece of this tomb appears to be intended to represent 

 the royal palace : an excellent engraving of it is given in Coste and 

 Flandin's ' Perse Ancienne.' The only example of a constructed tomb 

 occurs at Pasargadic, where a small temple stands on the summit of a 

 low pyramid of stone steps, around which, but at some little distance, 

 ia traceable a peristyle or colonnade : this is ascertained from the 

 descriptions in Greek writers to be the Tomb of Cyrus. 



(Sir R. K. Porter, Trarelt, vol. i. ; Chardin, Morin, Ac.,' Trarelt ; Hirt, 

 Bankunst ; Flandin and Coste, Perse Ancienne ; Fergusson, Palaces of 

 A'l'neirA and Pertepolis Restored ; handbook of Architecture.) 



PERSICA. [PEACH.] 



1'KKSON'AL ACTIONS. [ACTIONS.] 



PERSONALTY AND PERSONAL PROPERTY. [CHATTELS.] 



PERSPECTIVE, a term popularly given to an application of 

 geometrical principles, by means of which a pictorial outline of a 

 certain class of objects may be delineated on a plane surface. Thus 

 understood it has been defined to be the art of representing on a plane 

 surface the outlines of objects in the same forms, positions, and 

 relative proportions which they bear to each other in nature as seen 

 from a given point. A perspective representation corresponds in fact 

 to a section of a cone of rays, the apex of which is in, the eye of the 

 observer (62, 64). In other words, if a pane of glass were interposed 

 between us and any object or objects which we were viewing through 

 a small hole (or tight), and we were to trace on the glass an accurate 

 outline of the objects as they appeared on it, that outline would be a 

 perspective representation : and it is the purpose of the art of per- 

 spective to show how this may be done if the necessary data be 

 furnished. Perspective constitutes however only a specific case of a 

 more general application of the geometrical principles above alluded to, 

 which enable us to make constructions relating to geometrical solids, 

 bearing the same relation to geometry of three dimensions that 

 practical bears to theoretical plane geometry. In the present article 

 these principles will be explained, and their application to perspective 

 be shown (66 ct teq), specifically with reference to geometrical solids, 

 but capable of extension to the objects delineated in pictorial repre- 

 sentations. 



The analyst, in his investigations of symbolical expressions for the 

 relations of geometrical magnitudes, refers these, according to the 

 species of magnitudes under consideration, either to co-ordinate lines 

 on a plane, or to co-ordinate planes, assumed at pleasure in space. 

 [CO-ORDINATES.] The draughtsman, or practical geometrician, makes 

 bis constructions on the lines and figures themselves, when they lie 

 wholly in one plane ; and when he has to make constructions on 

 geometrical solids, he is compelled to refer the various points, lines, 

 and figures connected with or constituting those solids to one or more 

 -. to effect his object ; and from constructions on these planes he 

 can determine the unknown quantities of the original solids by means 

 of their projections, as they are termed, knowing the conditions under 

 which these projections were obtained. 



1. The series of points of any geometrical solid are most simply 

 supposed to be referred to a plane by parallel right lines, passing 

 through them perpendicular to the plane ; the intersections of these 

 lines with the plane are termed the projections of the original points on 

 that plane. 



2. Let us conventionally designate the original points by Italic 

 capital letters, and their projections by small letters ; thus p means 

 a point in space, p its projection on a plane. 



3. The points /, m, n, on a plane A Y z, are therefore understood as 

 referring to the points in space, situated in right lines passing through 

 I, m, n respectively, perpendicular to that plane ; but these projections 

 alone do not define the relations between the original points ; for I, m, n 

 are each the projections of an infinite number of original points, of all 

 in short through which each projecting line may pass. To define the 

 specific points L, M, x, we must consequently not only have /, m, n, 

 but the lengths respectively of the projecting lines Ll, am, nn, or 

 the distances at which L, it, x are respectively situated from their 

 projections. 



4. This second series of essential data is furnished by the projections 

 L, M, H of the original points on a second co-ordinate plane B Y z, per- 

 pendicular to the first, and therefore parallel to the former projecting 

 lines, by which l,m,n were determined; while, conversely, the first 

 plane must be parallel to the projecting lines by which L, M, N are 

 determined. For if a third plane be conceived to pass through the 

 two projecting lines LL, il, of any point L, and therefore necessarily 

 perpendicular to the two co-ordinate planes, the intersections of this 

 third plane with the two latter will, together with the two projecting 

 lines themselves, form a rectangle ; consequently the distance of any 

 projection L, from the common intersection v z of the co-ordinate 

 planes, is equal to the length of the projecting line L(, which is parallel 

 to it ; while, conversely, the distance of the other projection I of the 

 same point L from the same common intersection is equal to the length 

 of the projecting line L L. 



5. Let us designate the third plane just described as the projecting 

 plane of an original point. It follows as a corollary from this definition 

 of the plane, that the projecting planes of a series of points L, M, N are 

 parallel to each other, and perpendicular to both co ordinate planes, as 

 well therefore as to the common intersection Y z of those co-ordinate 

 planes. 



6. Let YZ always designate the common intersection of the two 

 co-ordinate planes; let the projections L, M, N be termed the plans, and 

 the projections I, m, n the deration* of the original points L, M, tt. It 

 follows that if an original point lie in either co-ordinate plane, its 

 projecting line will coincide with that plane, and its projection on the 

 other will be a point in Y z. 



7. Let us next consider a right line L M, supposed to join or pass 

 through two points in space L, n. Then the right line LM joining or 

 passing through the plans of /, and M, is called the plan of LM, and Im 

 is the elevation of the same original line. 



8. It is obvious, from the preceding definitions, that the plan and 

 deration of any original right line L n in space are the intersections 

 with the co-ordinate pknes respectively of two planes passing through 

 the original line perpendicular to the co-ordinate planes. 



9. We will distinguish the projecting plane of an original line L M, 

 by which the plan of that line may be conceived as produced, as the 

 plan-projecting plane of LM ; and the projecting plane by which Im is 

 produced, as the elevation-projeclhig plane. But the reader must not 

 confound the projecting plane of an original point, which is necessarily 

 perpendicular to both co-ordinate planes, with the projecting plane of 

 an original line ; which, though necessarily perpendicular to one 

 co-ordinate plane, may be parallel, perpendicular, or oblique to the 

 other, according as the original line is parallel, perpendicular, or 

 oblique to that other co-ordinate plane. Nevertheless the projecting 

 plane of an original line will always intersect that co-ordinate plane, to 



