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LONDON: VIRTUE BROTHERS & CO., 26, IVY LANE, PATERNOSTER ROW. 18G6. INTRODUCTION. In the course of twenty years' extensive practice as a teacher of drawing, the Author has frequently had considerable difficulty in making his juvenile pupils com- prehend the necessity for and the value of a knowledge of Perspective. Many works have appeared, proposing to enable the student and the amateur to instruct them- selves in this indispensable branch of the Art of Painting ; but the Author has never yet met with one that has appeared to him well calculated to accomplish so de- sirable an end. To furnish amateurs, and especially young ladies, with the means to acquire, by themselves, a knowledge of Perspective, sufficient to enable them to make agreeable sketches from nature, without sacri- ficing too much of the time that must be required for other occupations, has been the object of the Author. In the little work he now puts before the public, his principal endeavour has been to avoid every possible diffi- culty — every superfluous line. It is addressed to those who require a simple and comprehensive knowledge of Perspective, to enable them to avoid committing any of those gross errors, so constantly to be observed in the works of those entirely ignorant of it. He strongly ad- vises all desirous of drawing from nature to make them- selves masters of the modes here given for drawing various forms, so as to be able to apply them mentally in sketch- ing from nature. , It is universally admitted, that sketches ir INTRODUCTION. made by those who draw by their eye, having at the same time a thorough knowledge of Perspective, produce more agreeable paintings than those who draw entirely by rule. To demonstrate to the juvenile student the value of a knowledge of Perspective, let him examine the cut at the end of this Introduction, as also that at the end of the First Part. The first is a correct repre- sentation of a double cross in perspective, drawn, as it would appear, when quite new and perfect ; the latter (which is drawn over the same outline) is intended to re- present a similar cross in an ancient and dilapidated state. The student will perceive that the perspective drawing looks formal and uninteresting, while the other has an agreeable and picturesque appearance, though perfectly correct. The art of painting is to represent objects in nature as they appear to the eye ; but if any lines, either from time or accident, have lost their perpendicular or horizontal direction, great care should be taken in the representation of them, that they are so drawn as not to appear like faulty Perspective, but as the result of time or some other cause. It is the absence of formality that constitutes picturesque form. The Second Part, which is entirely new, and written for this Third Edition, carries the student still further, and opens to view all the requisite acquirements for a perfect knowledge of the art of Perspective. This edition will be found to comprehend all the principles, with simple representations, to enable the learner by ordinary appli- cation to execute perspective drawings with facility. CONTENTS. PART L Page Chap. I. — Explanatory Introduction 1 II. — Representation of Plane Surfaces bounded oy straight Lines .. .. .. .. ..14 III. — Representation of Plane Surfaces bounded by curved Lines . . . . . . . . . . . . 34 IV. — Representation of Solids . . .. .. ,.55 PART II. I. — I j near Perspective .. .. ..73 it. — Rules of Perspective deduced from the Science of Optics 81 III. — Number of Objects combined ... .. ..90 IV. — Objects changing require a fresh Vanishing Point . . 99 V. — How Solid Figures arc drawn in Perspective .. .. 107 VI. — In the projection of Roofs, Pediments, Cornices, Moulding, &c 139 VII. — On the choice of Position for the Spectator, relative to the Objects to be represented in Perspective. . . . 156 UST OF PLATES. Plate I. to face page IT. ft III. * * IV. V. ft VI. 1* VII. It VIII. ft IX. It x. XI. tt XII. tt XIII. »• 10 .. S3 .. 2i .. 23 .. 28 .. 35 .. 38 .. 43 .. 45 51 .. 5*? .. 59 .. 64 PERSPECTIVE FOR STUDENTS. CHAPTER L Students, from the first commencement of drawing, should never neglect an opportunity of submitting their pro- ductions to the inspection of those who, from their superior knowledge, may point out defects, and suggest alterations extremely useful. But in criticising their works, those who have attained some proficiency may frequently make use of terms which, though perfectly correct, may by possibility not be understood by very young pupils, and hence they may lose much valuable assistance. Before commencing Perspective, the pupil will therefore find it to his advantage to make himself acquainted with the following preliminary matters, which more properly belong to practical geometry. Many young persons, in copying a drawing, if they draw a line that is out of the perpendicular, or not horizontal, are apt to say, " That line is not straight." The first thing to comprehend is, that all lines lying evenly between their two extremities (which are called points) are straight lines, whatever direction they may take (Fig. 1). The line A b is a straight line, and each of the lines that run from it, and through it are also straight lines, although they vary in their direction. Lines that run in the same direction, and continue always at the same distance Perspective, B A 2 PERSPECTIVE FOR STUDENTS. from each other, are called parallel lines (Fig. 2). Lines which incline towards each other ^'S' 2 - and meet in a point, are said to form ~ angles. Angles have three different ~ names, according to the space con- tained between the two lines at an equal distance from their point of meeting (Fig. 3). The lines a E and c e meet together at the 3 ' point E ; the lines b e and c e also meet together at the point e : the space between a c and the space between B c will be found to be exactly equal. Whenever one line stands upon an other line, and, upon drawing a semi- circle from the point of contact (as the semicircle A c B, drawn from the point e), the line divides the semicircle into two equal parts, it is said to be perpendicular* to the line on which it rests, and the angle on either side is called a right angle. If the space contained between two lines forming an angle be less than that contained between the lines forming a right angle, the two lines are said to form an acute angle. The angle formed by the lines D e and a e is less than the right angle, because the space contained between a d is less than the space contained between c a : for the same reason, the lines c e and d e also form an acute angle. If the space contained between the two lines be greater than the space contained between the two lines that form the right angle, * It is a common error to confound the terms vertical and perpendi- cular. One line is always said to be perpendicular to another line when the angle formed by the two lines is a right angle. Vertical lines are those lines perpendicular to the horizon, or to the surface of the globe. If a vessel lie on the surface of the water in a dead calm, having her masts perpendicular to her deck, the masts may be said to be vertical ; but if the water were agitated so as to throw the vessel at an angle with the horizon, though the masts would still be perpendicular to the deck they would no longer be vertical lines. PERSPECTIVE FOR STUDENTS. 3 the two lines are said to form an obtuse angle. The angle formed by the lines b e and d e is greater than the right- angle, because the space contained between b d is larger than the space contained between b c. If the learner open a pair of compasses exactly half way, the legs of the compasses will form a right angle ; if they are shut-to a little, they then form an acute angle ; if opened a little wider, they form an obtuse angle. If the extremities of the two lines forming an angle are joined by a third line, the figure formed by the three lines is called a triangle, from its containing three angles (Fig. 4). In making perspective drawings, certain instru- ments are indispensable ; and one of the most essen- tial is a proper drawing-board, in the choice of which great care should be taken that the edge at the bottom be perfectly straight, and that at all events one of the sides be perfectly at a right angle with the line of the bottom — or, in other words, that the side of the board be perpendicular to the bottom : if not, and the pupil should make use of the T square,* his drawing can never be correct ; because all lines drawn with the T square are parallel : consequently, what- ever error may exist in the drawing-board will be multiplied by your ruler. To be certain that you commence with a perpendicular line, draw, as in the following example * The tee, or, as it is commonly written, from its form, T square, is a ruler to which is attached at one end a cross piece of wood ; and this cross piece, being made thicker than the ruler itself, enables the drafts- man to slide it backwards and forwards on the edge of his board. The ruler attached to this cross piece is exactly at right angles with it ; and consequently, in moving it along the bottom edge of the board, and drawing lines from it, the lines must all be parallel to each other, and perpendicular to the bottom line of the board. Now if the drawing- board have one of its sides at a right angle with the bottom edge, by shifting the T square from the bottom to the side of the board, and sliding it on this edge, all the lines ruled from it will be parallel to each other, and at right angles with the lines drawn from the bottom. The T square is the most convenient and quickest ruler for drawing all perpen- dicular and horizontal lines. B 2 4 PERSPECTIVE FOB STUDENTS. 4*- Fig. 5. (Fig. 5), with a ruler a straight lino, which is to form the bottom or base ( line of your picture. From the point on this line from which your per- pendicular line is to be raised, as at 9^ A, mark off an equal space on each side, as the spaces a b and a c ; from the extremity of each of these spaces, at the points b and c, with a pair of compasses, at an extension of not less than once-and-a-half the length of a b or a c, describe two portions or arcs of a circle immediately over the point A; from the point D, where these two arcs intersect each other, draw the line d a, which will always be perpendicular to the line a b, and may be continued to any length. The learner must be aware that in a work of this kind, illustrated by wood- cuts, the space for the insertion of the examples is extremely limited ; he is therefore recommended, in drawing them for his own practice and improvement, to enlarge them very considerably — say from four to six times the size. There are various other rules in practical geometry that the author has found useful to his pupils ; but as this is not a treatise on practical geometry, they are not given. The foregoing are introduced from a conviction that with the very young, they are nearly, if not quite, indispensable. In introducing my young readers to an elementary know- ledge of perspective, as the most simple definition, I should say that perspective is the art of representing objects at various distances, and is of two kinds — Aerial Perspective, and Linear Perspective. Aerial Perspective is the art of giving the appearance of distance, independent of lines. Claude de Lorraine is celebrated for his exquisite manner of representing aerial perspective : many English painters are also highly and deservedly celebrated for this portion of the art of painting, more particularly the painters in water- colours ; among whom, perhaps, Glover and Copley Field- ing have been the most successful. It is of the latter, Linear PERSPECTIVE FOR STUDENTS. 5 Perspective, that we have to treat : of this it may be said, that it is the art of drawing outlines of objects from nature, of their relative sizes according to their distance, and of their apparent variety of form according to their position, as they would appear in looking through a sheet of glass placed be- tween them and the spectator. The reader is doubtless aware that all objects of the same magnitude apparently diminish as they recede from the eye of the spectator. In walking in a long street at night, the reader must have noticed the appear- ance of the gas lamps as they gradually recede from him : if the street be very long, they will appear to come closer and closer together, till they apparently meet in a point ; * yet the more distant lamps are as far apart from each other as those close to the spectator. The same appearance is observ- able in a long avenue of trees. In a long series of arches, the first few will show their curves wide and distinct : as they recede from the eye they appear gradually narrower and nar- rower, till in the extreme distance they assume the appearance of mere straight lines. To demonstrate clearly to the young reader that objects at a great distance seem very small, let him look through a pane of glass, and imagine that this pane of glass were a sheet of paper, on which he had to re- present all the objects he sees through it : though this pane of glass may only be a foot square, he may see houses, ships, tracts of country, mountains, rivers, &c. &c. represented on this small space, though perfectly aware of their actual size. Most of my readers must have heard the term horizon frequently used in conversation — in such cases as " the sun is above the horizon," or, " the sun has sunk below the hori- zon," 'Ssc Every perspective drawing has a line running across it, parallel to the bottom of the picture, to designate the line of the horizon, which line is called the horizontal line. In drawing from nature, this line is at a height exactly level with the eye of the draftsman ; and its position, or dis- * This point is termed the vanishing point, and is most important, as will be seen in our progress. 6 PERSPECTIVE FOR STUDENTS. tance from the base of the picture, which is called the ground line, depends entirely on the position in which the artist places himself to take his sketch. In the following example (Fig. 6), we will suppose the lines 1, 2, 3, 4, to form the j,. g boundary lines of the pic- ture. If the draftsman is placed in a sitting pos- ture, as at a, the hori- zontal line will be at the height of the line 5, even with the painter's eye, and parallel to the ground line 1. If the draftsman stand up to take his sketch, as at B, the horizontal line will be higher, in conse- quence of his eyes being in a more elevated situation, and will be at the line 6. If, to get into his picture some more distant object, the artist should find it necessary to raise him- self still higher, as at c, upon the bank, the horizontal line will also be raised, as seen by the line 7 ; or, as I have before stated, the height of the horizontal line depends on the raised or lowered position of the eye of the artist. In making a picture, the choice of height of the horizontal line is of considerable importance. To make the horizontal line exactly half- way between the top and bottom of the pic- ture, has generally a bad effect ; it appears to cut the picture in half, and the perspective is not pleasing to the eye. It is generally considered that the most agreeable perspective is produced by placing the horizontal line at about one-third the height of the picture from the ground-line : to place it lower than this is generally preferable to placing it higher. There are painters, however, of great celebrity, who in some of their finest productions have placed their horizon so high as to be removed only one-third from the top of the picture. Gaspard Poussin, Francesca Mola, Domenichino, &c. have frequently painted pictures with these high horizons ; but the PERSPECTIVE FOR STUDENTS. 7 subjects are peculiar, and the painters so talented, that any- thing emanating from their pencils cannot fail to be good. All those views that come under the denomination of bird's- eye views must necessarily have the horizontal line very high, being taken always from some high window, tower, or eminence of some sort, such as the views of London from St. Paul's, of Paris from the Pantheon, &c. &c. ; but such views are intended more for topographical curiosities than for pictorial representations. In order to give the reader an idea of the use of perspec- tive, we will commence with some object of the most simple form, a square, or oblong (figures which are technically called rectangular parallelograms, from their opposite sides being parallel to each other, and the angles all right angles). Let the student take any rectangular object — a workbox, for instance ; let him place it in front of him, close to his feet, then bend his head slightly forward till his eyes come imme- diately over the centre of the box (Fig. 7) : so placed, he will be able to see nothing but the simple form of the lid, it being impossible in this position to see either the front, back, or sides. Let the student now place the box on the chimney-piece, the front towards him, and place himself about two yards from it, and in such a position that his eyes shall come on a level with the middle of the front of the box, and exactly midway between its two sides (Fig. 8) : thus placed, the student will see nothing but the front of the box, it being impos- sible in this position to see either the top or sides. The student must now place the box on a chair, or other support, so as to be in height about halfway between his head and feet, placing himself at two or three Fig. 9. yards' distance from the object, but still in such a position as to stand exactly opposite the key- hole of the box (Fig. 9) : he now, from the changed position, sees the top and front of the Fig. 7. Fig, 8. 8 PERSPECTIVE FOR STUDENTS. box. Let the student now shift his position about one yard to the left, leaving the box in the same situation ; he will here find that he sees the front, the top, and one side of the Fig 10 k° X (Fig* The student will here ob- serve, that according to the variation of the position from which he regards the object, it changes its apparent form. In the first two figures he will see that the lines are all parallel to their opposites, or, as it is commonly called, are in geometrical drawing ; but in the third figure he will per- ceive that the lines of the sides of the top converge, and that the line of the top of the box at the back is shorter than the line of the top in front. Perspective teaches how to find the proper directions for these converging lines, and also shows now to regulate the length of the line at the back of the box, so as to make it agree with its apparent diminution of size to the visual organs. The same remarks apply equally to the last figure. As another example of the use of perspective, let the student procure a common bowl, and place it at his feet, looking at it in a similar manner as at the workbox in its first situation. In looking at it in this position, the student will Fig. 11. see nothing to draw but a plain circle (Fig. 11). If the bowl be placed on a chair, as the work- box in its third situation, the spectator being in the same relative position, the circular opening of the bowl appears of only half its width, and a Fig. 12. portion of its outer part is seen (Fig. 12). If the s \ bowl be now placed on the chimney-piece, and v" y the eye of the spectator brought to a level with the upper edge of the bowl, none of the inside Fig 13 °^ ^ e ^owl is perceptible, the circle from this point of view appearing as a straight line (Fig. 13). The student will here observe that, accord- ing to the position in which the spectator is placed relatively to a circular object, it takes the PERSPECTIVE FOR STUDENTS. 9 form of a circle, an ellipse, or a straight line. Perspective teaches how to delineate the form the circle apparently as- sumes, according to the point of view from which it is seen. In the preceding pages we have introduced four diagrams, representing the change of appearance a work-box, or any similar object, assumes, as viewed from four different posi- tions. In the first and second figures, the upper and lower lines of the box are parallel, as are the upright lines repre- senting the sides ; they are in fact of precisely the same form as that they are intended to represent, the position in which they are viewed presenting the simple geometrical figure. The third position of the box presents the front, similar to the second, but being below the eye, the top as well as the front of it is seen. Now, as objects appear smaller as they are further removed from the spectator, the back of the box will appear less than the front, and Fig. 14. must necessarily be represented by a shorter line ; hence it must be obvious that to draw the lines re- presenting the sides of the top, they must incline towards each other, and if continued, would meet in a point, as in the annexed figure. In the fourth diagram, the front of the box is still drawn geometrically, but from its position being again changed relative to the spectator, both the top and one side of the box, as well as the front, are vissible ; and as the lines representing the back of the top and the further angle are both drawn shorter than the front edge Fig. 15. and nearer angle of the box, the lines drawn to represent the sides of the top and the side of the bottom must in- cline towards each other, and the three lines would, if con- tinued, meet in the same point. Now these three lines, which in Figure 15 incline b 3 10 PERSPECTIVE FOR STUDENTS. towards each other so as to meet in the same point, in the original object (the workbox) are parallel lines; and herein consists the difference between what is called Geometrical or Elevation drawing, and Perspective drawing. In the former, all lines that are parallel in the original object, are drawn parallel in the representation ; whereas in perspective drawing all representations of parallel lines incline towards each other, and tend to the same point. This point is always placed on the horizontal line, and is called the vanishing point. Thus, D in the foregoing figure is the vanishing point for the lines abc, and would be the point to which all lines which in the original object are parallel to those they represent (the side edges of the box) would be drawn, however numerous ; this is exemplified by the line e, showing where the lid of the box shuts on. It is to be presumed, that before commencing the study of perspective, the student has already dabbled a little in drawing ; in which case he must now make an attempt to draw a little perspective for himself. Let him place himself in a chair, immediately opposite a closed door, and at a distance of six to eight feet, and in that position let him draw the door, and the cornice if any ; if not let him sketch a little of the pattern of the papering above the door, as in fig. 1, Plate I., which is a geometrical drawing of a door, to be put in perspective. Let the student now imagine a straight line passing di- rectly from his eye to the door, always at the same height from the floor — or, more correctly speaking, parallel to the floor : this line would touch the door at the point A ; and this point fixes the height of the horizontal line, and is called the point of sight.* But we must here proceed with the second figure, Plate I. The student must first draw the four outer lines of the * The point exactly opposite the eye of the spectator is always termed the point of sight, and forms the perspective centre of a picture : when used as a vanishing point, it is for those lines only that are parallel to the imaginary straight line passing from the eye to it. PERSPECTIVE FOR STUDENTS. 11 door, b c D K, as in the geometrical drawing, and then through the point A (the height of his eye from the ground) draw a line across his picture parallel to the ground line, or bottom line of the drawing ; this is the horizontal line. In looking at the geometrical drawing (fig. 1), it will be seen that the two lines b c, which represent the two sides of the door, from each of them being at the same distance from the eye of the spectator, are of an equal length ; that the lines D and k, representing the top and bottom lines of the door, are parallel to each other ; and that the lines representing the top and bottom of the panels are parallel to each other, and to the lines d and K also. Let the student now open the door about one foot : here he will observe an extraordinary difference ; — the directions of all the horizontal lines,* as seen in the geometrical drawing, are now changed. Observe that the upper and lower corners of the door, 1 and 2, the side where the hinges are fixed, remain the same as in the geometrical drawing: they have not changed their situation, but the corner 3 appears raised, and the corner 4 lowered, making the side c of the door consequently appear longer; the side of the door c, from its being approached nearer the eye, becomes apparently larger ; but the side b, as it remains in precisely the same position, remains of the same size as in the geometrical drawing. The student must now carefully notice at what particular spot on the cornice, or at what particular mark on the pattern of the papering, the point 3, marking the top of the door, appears to touch, and mark the spot on his drawing, as at A : from this point, through the point 1, marking the other corner of the top of the door, the student must draw a line till it touch the horizontal line ; and the point l, where it touches, is its vanishing point. Now the student must bear in mind, that this vanishing point is * All lines in a drawing that are parallel to the horizontal line are called horizontal. The student must understand that the line drawn through the point a is the Horizontal Line, or line representing the horizon ; and that those lines parallel to it are only called horizontal in reference to their being parallel to it. 12 PERSPECTIVE FOR STUDENTS. the point to which every line of the door, parallel to che line of the top of the door in the geometrical drawing, must be drawn in his perspective drawing, whether above or below the horizontal line. In order to get the perspective line of the bottom of the door, the student must place his ruler to the vanishing point L, and draw a line through the point 2 till it passes nearly under the right-hand side of the door : to determine the length of this line, the student must draw a perpendicular line from the point 3 till it meets it at the point 4. The student should now, with a firm hand draw over the lines b, c, d, k, to make them stronger than the other lines ; and he will then have the external lines of the door in perspective, as it appears to him from the position in which he is placed. The next thing necessary is to find the perspective inclinations of the lines forming the top and the bottom of the panels of the door — the lines e, f, g, h, i, j, of the geometrical drawing. To accomplish this, the student must mark upon the line B the relative distances of these lines, as at the points 5, 6, 7, 8, 9, 10; and from the vanish- ing point l through each of these points he must draw a line till it touch the line c. Here, then, are all the horizontal lines of the panels of the door in their perspective directions : and the student will observe that the panels of the door, as also the framework of the panels, gradually widen as they approach the eye of the spectator, or, in other words, they diminish as they recede from it. Having obtained the lines which will regulate the height of the panels, it is now neces- sary to determine their width. It must be obvious to the readei, from what has already been said, that the framework surrounding the panels must be wider on the side nearest to him than on the side at the greater distance. To find the width of the panels, the student must draw a line parallel to the horizontal line from the point 3 of the geometrical length of the top of the door, and measure off with his compasses from each extremity, 3 and 11, a space equal to the width of the framework of the panels, as at 12 and 13, the space between being obviously the width of the panel. From the PERSPECTIVE FOR STUDENTS. 13 point 11, passing through the point 1, a line must be drawn till it touch the horizontal line, as at m ; and this point is called the point of distance, by which the perspective width of all the spaces between the perpendicular lines upon the door may be ascertained. From the points 12 and 13 two lines must be drawn to the point of distance, m ; and where these lines intersect the line d, at 14 and 15, they mark the perspective width of the framework or panels on the top of the door: from these points, 14 and 15, two perpendicular lines must be drawn till they touch the line K ; and where these perpendicular lines pass between the lines E and f, g and H, and i and J, they form the perpendicular boun- daries of the panels. The student must now strengthen all the lines of the panels, as in the example ; and he has com- pleted his task, — he has drawn the door in perspective. In order to make the foregoing example simple enough to be comprehensible to the most inexperienced, the drawing is confined to the fewest possible quantity of lines. The thickness of the door and the projection of the framework round the panels has been purposely omitted, — a multiplicity of lines tending always to perplex the learner; but the rules for drawing these are the same as those already explained. That the student may satisfy himself that he has clearly understood what he has just accomplished, let him open the door so wide as to bring the handle of the door within a foot of the wall, and reseat himself in the same position. He now loses sight entirely of the side of the door he has just drawn, and the outer side becomes visible. The point of sight, and consequently the horizontal line, is precisely the same, but the vanishing point of the door changes sides : instead of being to the left of the artist, it is now to his right hand ; the whole drawing of the door is reversed, but the process of putting it in perspective is precisely similar to that of the last example. It is strongly recommended to the student to proceed carefully and steadily to draw it in this altered position. 14 PERSPECTIVE FOR STUDENTS. CHAPTER II. The Author, when very young, on being strongly recom- mended by an artist, now an R. A., to draw from nature, replied that he had no possibility of getting into the country. " My young friend," said Mr. C , " you have got a notion, like many other foolish people, that to draw from nature it is necessary to go into the country. Let me advise you, if you cannot find a tree to draw from, to draw the plants in your mothers flower-pots ; if you cannot get to draw the outside of a house, draw the inside of a room ; if you are unable to find a wheelbarrow, take a coal-scuttle ; if cows and sheep are not to be found, draw the family cat ; — you will find it equally improving, and it will give you the power ultimately of representing every object you desire on paper." The advice was most excellent ; and the Author most strongly recommends it to his juvenile readers. He is about to lead them step by step to draw various objects in perspective ; and the forms selected will be the most familiar and the best adapted to the purpose : but in the limits of a small work like this the principles on which certain objects may be represented in drawing is all that is attempted. If an example of a square object is given, the rules for drawing that square object will apply to everything of a similar form seen from a similar point of view. If an example is given for drawing a circular, octagonal, or any other form, all similar forms may be drawn by the same rules. Once clearly comprehend how to draw a circle in perspective, and it is immaterial what circular object is to be represented : the same rules apply to all, whether a plate, a tumbler, a column, or a dial, &c. One of the great difficulties experienced by teachers is that of making their pupils understand the manner of finding the Vanishing Points and Points of Distance. For architectural PERSPECTIVE FOR STUDENTS. 15 draftsmen, and those who go deeply into perspective, there are rules by which all the various points are to be found ; but they are perplexing and tedious, unfitted for an elemen- tary work like this, and unnecessary for those whose object is simply to acquire that knowledge of perspective which will enable them to make correct and agreeable sketches from nature. In order to find the Vanishing Points, some teachers recommend their pupils to make use of an instrument called a moveable angle, or guiding-rule. It is an instrument of this form. (Fig. 16.) It is made simply of three straight pieces of wood, the two outer pieces of which, by means of a moveable screw, open and shut like a pair of compasses. The use of it is, to hold it at arm's length, between the spec- tator and the object to be represented — as, for instance, the two top lines of a church tower — and, by means of the screw, move the legs of the guiding-rule till they follow the direction of the inclination of these two upper lines ; then, laying the guiding-rule on your paper, and placing the point formed by the angle over the point representing the highest point of the nearest corner of the tower, rule the lines in the direction of the two- sides of the guiding-rule, and continue them till they touch the horizontal line. The points where these lines would touch would form the vanishing points for the horizontal lines on the respective sides of the tower. Presuming that the reader draws a little before attempting to draw from nature (and if not, he is strongly recommended so to do), the author considers it far preferable for the drafts- man to depend rather on his eye and judgment than to make use of a guiding-rule or other mechanical instrument ; that he make his first sketch by eye, and correct it afterwards by the rules of perspective. Problem I. — Let the student imagine himself placed before a cottage, having a gable at one end and four win- dows in front, and let him further imagine that he is so 16 PERSPECTIVE FOR STUDENTS. situated as to see both sides nearly equal — that he stands, in fact, nearly in a line running from the angle formed by the Fig. 17. lines J K to the corresponding corner, ■~ which is hidden. (Fig. 17.) Suppose A to be the plan of the house, and B the position of the draftsman, c would represent the line drawn from the spectator's eye to the point of sight : and the student will perceive that the lines r> and e, the two sides of the house visible, are neither of them in the direction of this line c ; consequently, that the point of sight cannot form the vanishing point for any lines running parallel to either D or E ; and that as these two lines are also at an angle, each of them must have its respective vanishing point : the line D will have its vanishing point to the right, and the line e to the left. The student, if sketching from nature, must first draw, according to the best of his judgment, the first upright line, a, of the building, and set a mark upon it at the height of his eye, in order to get the horizontal line. To make this perfectly simple, we will suppose the real height of this line to be twenty feet, and that the spectator is so situated as to have his eye at five feet from the ground ; he must then measure off from the bottom of the line one-fourth of its length, which will give the height of his e^e at five feet from the ground ; and through this point he must draw a line, B, across the picture, which will form the horizontal line.* * The student must here bear in mind that the height of the hori- zontal line depends entirely on the situation in which he is placed. If the building from which he is drawing stood on a rising ground, say a rise only of five feet, the horizontal line would be exactly on a line with the base of the building, the spectator's eye being supposed five feet from the ground on which he stands. If, on the contrary, the spectator stood on a rise of five feet, the horizontal line would cut the line a in half, because, the house being twenty feet, the spectator's eye, being five feet above the spot on which he stands, would bring it to ten feet high. If the spectator stoof on a rise of fifteen feet, the horizontal line would PERSPECTIVE FOR STUDENTS. IT From the top of the line A the student must now sketch the lines c and D, marking their inclination towards the hori- zontal line as carefully as possible, and he must then sketch the lines e and F, to determine the width of the two sides of the building. This is all that is necessary for the student to draw by eye, and he must now correct his sketch by rule. He must first, with his T square, the use of which has been already described, make the line A perpendicular, so as to be at right angles with the horizontal line on each side, both above and below it : he must then, placing his rule upon the top of the line a, marked 1, in the direction he has sketched the line c, rule a line till it meet the horizontal line at g, which will be the vanishing point for all the horizontal lines on the left side of the house. From the same point 1, the top of the line a, following the direction of the sketched line D, another line must be drawn till it meet the horizontal line at the point H, which will be the vanishing point for all horizontal lines on the right side of the house. The rule must now be placed at the point 2, the bottom of the line a, and from it to the vanishing points, g and h, the lines J and k must be drawn, which lines represent the perspective inclination of the bottom lines of the house, as the lines c and d represent the perspective inclinations of the top lines. The lines e and F, determining the width of the two sides of the house, must now be corrected by the T square, taking care to draw the line e so as exactly to meet the lines c and J at the points 3 and 4, and the line f so as exactly to touch the lines d and K at the points 5 and 6. Here let the student well notice these three lines, a, e, and f, which, though really of the same height in nature, are all dissimilar in the perspective drawing. The line A, from being the nearest to him, appears the longest ; the line E, from the left side of the house being be on a level with the top of the house. Practice, and attentive exami- nation of the works of clever artists, will gradually teach the amateur a good choice of position, upon which the agreeableness of his drawing greatly depends. 18 PERSPECTIVE FOR STUDENTS. narrower than the right, is nearer to the spectator than the line f, and is consequently, though considerably shorter than the line a, much longer than f, the farthest removed from the eye. The upper part of the left side of the house is terminated by a pointed roof, or what is called a gable, and the point of this gable in nature is perpendicularly over a point mid- way between the lines a and e. The student must be aware that the perspective centre of the side of the building cannot be exactly half-way between the lines a and e in the drawing, - because that half of the building nearest to him must appear wider than the half that is farther off. If the centre is required of any rectangular parallelogram, it is found by Fig. 18. ruling two lines from its opposite angles, which are \ a called diagonal lines (Fig. 18), the intersection of X. which denotes the centre of the figure. So in per- ^ spective, — the space contained by the lines a, c, e, j, is a rectangular parallelogram in perspective ; and if from the opposite points, where these lines join, as from 4 to 1 and from 3 to 2, the diagonal lines l and m are drawn, the point where they intersect at 7 is its perspective centre,* and the point of the gable must be drawn directly over it ; to do which the student must draw a perpendicular line n through this point 7 above the line c ; and at some point on this line the lines forming the sides of the gable must meet. In order to determine the height of the point of the gable, the student must continue the line a above the point 1. This line being the nearest perpendicular line, is the most convenient for finding the height of all objects on either side of the house. Let us suppose the height of the point of the gable to be five feet above the line c ; this five feet must be set upon the line A, above the point 1. The student must therefore put on this line one-fourth of its length, as at 8, and from it (the * This mode of finding the perspective centre of a parallelogram by diagonal lines is eminently useful in sketching from nature ; it often obviates the necessity for a great many points and lines that would other- wise be needed. The student will do well to bear it in mind. PERSPECTIVE FOR STUDENTS. 19 point 8) rule a line o to the vanishing point where this line intersects the line n is the perspective position of the point of the gable, to which, from the points 1 and 3, draw the lines p and q, which complete the drawing of the left side of the building. The student is here shown the method of finding the exact perspective height of the point of the gable ; but in sketching from nature it is quite sufficient to choose the point on the line N by the eye, and from it rule the lines p and q, — as whether it is a trifle higher or lower is of little importance. The mode used for finding the position and width of the windows, is similar to that for drawing the panels and frame- work of the door, in Fig. 2, Plate I. From the point 1 a horizontal line R must be drawn, to represent the geometrical length of the line d in the perspective drawing ; * and on this line must be measured off at each end the distance of each window from the side of the house, as at 10 and 13, and from each of these points the width of each window, as at 1 1 and 1 2. From 9, the extremity of this line R, a line must be drawn through the point 5, till it meet the horizonial line at s ; which point forms the point of distance, by which the width of all objects on the right side of the house is deter- mined. From each of the points on the line R, viz. 10, 11, 12, 13, a line must be drawn to the point of distance, s; and where these lines intersect the line d (which represents r in perspective) they designate the perspective positions of these points, from each of which a perpendicular line, as 14, 15, 16, 17, must be drawn, till it touch the bottom line, K, of the building. The space between a and 14 represents the per- * It is immaterial to what length the line r is drawn, so that it be longer than the line d. The student must be aware that r, being the geometrical line represented in perspective by the line d, must necessarily be the longest. If the line r were lengthened so as to bring the point 9 further to the right, but keeping the distances and width of the windows in their relative proportions, the point of distance would be further to the left, but the intersections on the line d would be the same. 20 PERSPECTIVE FOR STUDENTS. epective distance between the side of the house and the first window; that between 14 and 15, the perspective width of the first window; from 15 to 16 is the perspective width of the space between the two windows ; from 16 to 17 the per- spective width of the second window ; and from 17 to the line F the perspective width of the space between the last window and the farther side of the house. It now only re- mains to determine the height of the windows, and their respective distances from the top and bottom lines of the building. Let us suppose that the upper window is one foot below the line d, and that the window is four feet high ; a twentieth part (one foot) must be marked off on the line a below 1, as at 18, which will be the geometrical distance of the top of the window from the roof, and below this one-fifth of the line A (four feet), as at 19, which will be the geome- trical height of the windows, and from each of these points a line must be drawn to the vanishing point H. Where the line drawn from 18 passes between the lines 14 and 15, and 16 and 17, it gives the perspective drawing of the top of each of the upper windows ; and where the line drawn from 19 passes between the same lines, 14, 15, and 16, 17, it gives the perspective drawing of the bottom lines of the upper windows. Supposing the lower windows to be of the same height as the upper ones, and that they are three feet from the ground, these distances must be placed on the line A ; that is to say, from the bottom, 2, of the line A, must be set up three-twentieths of its length (three feet), as at 20, and above that one-fifth of the length of a (four feet), as at 21. From each of these points, 20, 21, a line must be drawn to the vanishing point h ; and where these lines pass between the lines 14, 15, and 16, 17, they give the perspective draw- ing of the top and bottom lines of the lower windows.* * The student should now draw in with a pen the strong lines, leaving the remaining lines, as well as the letters and figures, in pencil, and care- fully preserve his drawings, as he will find them always useful, and towards tLe end of the work they may save him much time and trouble. PERSPECTIVE FOR STUDENTS. 21 It is hardly necessary to tell the student, that the dark lines in the plates represent only the object to be drawn, and that the faint lines are those used for finding the correct per- spective. In the foregoing example, on the right side of the drawing, the student is made to comprehend a mode for finding the perspective distance and size of any object on the face of a building : the forms chosen — the windows — are rectangular figures, as being the most simple ; but the posi- tion and size of any object, whatever may be its form, can be ascertained by the same rule. In our progress we shall endeavour to render intelligible the mode of putting a variety of forms into perspective ; but, like everything else, it is necessary to proceed step by step, and to thoroughly understand one problem before proceeding to another. On the left side of the building the student is made to comprehend a mode for putting a pointed roof or gable in perspective ; and, simple as it is, it is surprising the number of errors constantly committed by the neglect of its use. The author has seen many paintings where the artist, from mere carelessness, has brought the point of the gable nearer to the line represented by a than to the side represented by e, which is most offensive to the eye. Many of the Dutch and Flemish paintings show a great deficiency in perspective drawing ; and the great Teniers, notwithstanding his beautiful representations of still-life, sadly outrages perspective in some of his out-of-door scenes.* Problem II. — In the foregoing example, the mode for finding a point of distance is given upon a line above the horizontal line : but many instances occur in drawing per- spective where all the lines are below the horizon ; as, for instance, a chess-board placed on a table, where, even in a sitting position, every line must be below the eye, or the * There is an entertaining print by Hogarth, the title of which I do not recollect, that would amuse, and at the same time be useful to the young reader : in it he has outraged perspective as much as possible. The btudent would do well to examine it and find out its errors. 2? PERSPECTIVE FOR STUDENTS. squares on it could not be seen. The student should place a chess-board before him, so as to view it in the same position as that represented in the plate. He must first sketch, to the best of his judgment, the square of the board a, b, c, d.* The line A must be drawn over with a rule, to make it per- fectly straight ; and parallel to it, at the distance the eye is above the board, a long line, e, must be drawn across the picture to represent the horizontal line. From the point 1 — the nearest left-hand corner — in the direction of the sketched line b, draw a line till it touch the horizontal line E at F, which will be the vanishing point. From the point 2 — the nearest right-hand corner of the board — a line must also be drawn to the vanishing point F. These two lines, B and D, represent the perspective inclinations towards the vanishing point of the two sides of the chess-board ; and the student will perceive how easily the two sketched lines are corrected. At the distance of from a to c, and parallel to A, a line must be drawn between b and d, to touch them at the points 3 and 4. The lines a, b, c, b, represent the outer lines of the chess-board in perspective. In order to regulate the perspec- tive widths of the squares, which gradually diminish from the line A to c, it is necessary to find a point of distance. The chess- board being a square, the student will understand that the line b, between 1 and 3, is the perspective length of the line a, between 1 and 2. If the student then rule a line from the point 2, making it pass through the point 3, and continue it up to the horizontal line, the point g, where it touches, will be the point of distance, and will regulate the perspective lengths of the squares on the line B.t The line * The dotted lines represent a sketch of the square of the chess - board, as it might be made by a beginner, to show with what facility a very indifferent sketch may be corrected by rule. f It is immaterial whether the line b or the line d, each of which represents the perspective length of a, be taken for rinding the perspec- tive distances of the squares. If the student measure off to the right of the point 2 a space equal to the line a, between 1 and 2, and from its PERSPECTIVE FOR STUDENTS. A mast now be divided into eight parts ; and from each oi the points of division, viz. 5, 6, 7, 8, 9, 10, 11, a line must be drawn to the vanishing point f. These lines represent the gradually decreasing width of the squares from a to c. From each of these points — 5, 6, 7, 8, 9, 10, 11 — a line must be drawn to the point of distance, G ; and where these lines intersect the line B, at the points c, d, e, /, g, they represent the gradual decreasing length of each square from A to c. From each of these points of intersection, a, b, c, &c. a line parallel to the line A must be drawn till it meet the line d ; and these lines, by their intersections with those drawn from the points 1, 2, 3, &c, give the perspective representa- tion of the whole 64 squares of the chess-board. The alter- nate squares are slightly shaded, to make the figure perfectly intelligible to the juvenile student. Here let it be understood, that when the four sides of the square, a, b, c, d, are put in perspective, if, in order to find a point of distance, a line had been ruled from the point 1 through the point 4, the point at which that line would touch the horizontal line would give a point of distance that would have produced the same result ; observing, that in this case the points of intersection, a, c, J, &c, would have come on the line D instead of the line B. Problem III. — The student, in drawing this figure, must, according to the explanations given in Problem I., draw the nearest house, so far as it is described, up to the lines lettered to q, and figured to 8 ; observing that, with a view of exercising his ingenuity, the gable end is on the opposite side, — the letters and figures up to q, and 8 referring to similar lines in Problem I. In* order to determine the perspective width of the second extremity, h, rule a line to the point of distance, it will intersect the line c at 4, the point determining the length of the line d by means of the hori- zontal line drawn from the point 3 of the line b. * It must be understood that the description here commenced, and continued to the end of this and the following paragraph, is not the 24 PERSPECTIVE FOR STUDENTS. and third houses, the same means might be used as employed for determining the position and width of the windows in Problem I. ; that is, a horizontal line might be drawn to the right of the point 1, the top of the line A, and from any part of the horizontal line to the left of the line e a point might be chosen as a point of distance ; and from it a line drawn through the point 3 till it meet this horizontal line, would give the geometrical width of the house between its point of contact and the point 1. If two similar spaces were mea- sured off on this line to the right, to represent the geometri- cal width of the second and third houses, and from each of the points of division a line were drawn to the point of dis- tance, where these lines intersect the line c would be the perspective widths of the second and third cottages. If the reader has thoroughly understood the First Problem, he would now have no difficulty in putting the gables to these two further houses, on the same principles as those used for drawing the first : but the author, in a long experience of teaching, has found so frequently that in the slightest varia- tion in the application of a rule the juvenile student is apt to get bewildered, that, at the risk of being thought tedious, he will repeat the mode necessary for proceeding. From each of the points of intersection on the line c, that determine the perspective widths of the second and third cottages, a perpendicular line should be drawn down to meet the line J ; and these two lines, with the portions of the lines c and j lying between them, would represent the rectangular parallelograms of the second and third cottages, answering to that contained by the lines a, c, e, j, of the first. In each of these perspective parallelograms two diagonal lines should description of the mode by which the gables in this representation are drawn. It is given in order to impress on the mind of the reader what he has already done, and to accustom him to comprehend perspective drawing by general description. The student would do well, however, to draw the problem on a separate sheet, according to the description nere given. PERSPECTIVE FOR STUDENTS. 25 be drawn, corresponding with the lines l and M in the first ; and from their points of intersection two perpendicular lines should be drawn to touch the line o, similar to the line N drawn from the point 7 to 9. The line o ruled from the point 8 to the vanishing point G fixes the height of the first gable ; and as it is supposed that all three of the gables are of the same height, the line o would also determine the height of the gables of the second and third cottages : so that where the line o would meet the perpendicular lines just drawn, would be the points where the two sides of the gable must meet. From each of these points to the top of the per- pendicular lines right and left (corresponding to the points 1 and 3 of the first gable) draw the sides of the gables, corre- sponding to the lines p and q of the first ; and in a similar manner any number of cottages with gables may be con- tinued on. Where many gables follow in succession, as in a long row of houses with gable ends, or with garret or other windows having pointed tops, there is a rule for putting them in per- spective much more simple than the foregoing, the use of which, with a little extra attention, the student will fully comprehend. Let us suppose that on some part of the front of each of these cottages was fixed a clock-dial, and let us further suppose the time marked upon each dial to be a quar- ter to twelve : the hour-hand of the dial would then be per- pendicular, (or so nearly so, that, for the sake of our lesson, we must grant it to be perpendicular,) and the minute-hand in a horizontal position. To represent a series of dials with the hands in this position would not require any additional points, because the hour-hands, being perpendicular, would be parallel to the other perpendicular lines on the face of the building ; and the minute-hands, being horizontal, would be drawn to the same vanishing point as the other horizontal lines on the face of the building: but if, instead of the hands of the dials indicating the time a quarter to twelve, they stood at ten minutes to five, they would then be at an angle both Perspective* C 2G PERSPECTIVE FOR STUDENTS. with the horizontal and perpendicular lines of the building. It has been already remarked, that all lines that are geome- trically parallel are drawn in perspective to the same vanish- ing point. Now if the hands of all these dials stand precisely at ten minutes to five, all the minute-hands must be parallel to each other, and all the hour-hands must also be parallel, and certain points must be found by which the directions of the lines representing these hands may be drawn. The minute-hands of the dials pointing to the figure ten, the lines representing them must necessarily run upwards from the horizontal line, and some point must be found to repre- sent them above it ; but where, on the contrary, they point to the figure five, they would run downwards, and some point must be found to represent them below the horizontal line. These points are to be found on a line perpendicular to the horizontal line, either above or below it, and passing through the vanishing point. As it would be with the hands of a series of dials just described, so is it with the lines corresponding with p and q in a series of gables, these lines being at an angle both with the perpendicular and horizontal lines of the building and with each other. By finding the respective vanishing points for these two lines, the student will not only be enabled to find the perspective directions for an infinite number of gables, but in drawing them they determine the perspective width of each building. To proceed with the drawing, which we left with the first house completed, as in Problem I. to the letter q and figure 8. Through the vanishing point G a long line R must be drawn perpendicular to the horizontal line, above and below it ; and the line P of the first gable must be continued upwards till it meet the line R at s, which will be the vanishing point for all the lines forming the left sides of the gables ; all of which lines the student is aware are geometrically parallel. The line q, the second line of the first gable, must then be con- tinued downwards till it meet the line r at t, which will be PERSPECTIVE FOR STUDENTS. 27 the vanishing point for all the lines forming the right sides of the gables. From the point 3 a line must be drawn to the vanishing point s, which will give the perspective direc- tion of the first line of the second gable : and where this line at 10 intersects the line o (which drawn from the point 8 regulates the height of each gable), it determines the point where the two lines of the second gable meet ; and from it a line must be drawn to the vanishing point t, which gives the perspective direction of the second line of the second gable. Where this line intersects the line c, which gives the perspective height of all the lines from which the lines of the gables are drawn, it determines the perspective width of the second cottage, and from it the third gable is drawn pre- cisely as was the second from the point 3. By the same process a fourth, fifth, or more gables may be drawn, at the will of the artist ; the three given are quite sufficient to enable the student to comprehend the rule. But one of the most important features of this mode of representing the gables, is the facility and accuracy with which the perspec- tive direction of the sloping line of the roof from the point 5 on f is drawn. It is a common error to draw this further line v parallel to the line p ; but the student will readily perceive, from the example before him, as also by looking at nature, the inaccuracy of so doing — the further line v sloping much more than the line p. From the point 9, the point of the first gable, draw the line u to the vanishing point h ; this gives the perspective direction of the upper line of the roof : then from the point 5 draw the line v to the vanishing point s; and where this line intersects the line u at 11 is a point corresponding to the point 9 on the line p. From each of the points of the second and third gables a line must be drawn to the vanishing point H, to give the direction of the upper lines of the roofs of the respective cottages, which completes the drawing. These additional points, s and t, are found to be valuable in various ways, as will be shown in our progress onward : they greatly facilitate the findiug, C 2 28 PERSPECTIVE FOR STUDENTS. the positions of chimneys or windows on sloping roofs of houses, of towers or soires on the sloping roofs of churches, &c. The student will perceive that diagonal lines are put on the gable end of each cottage, and that perpendicular lines have been drawn from their points of intersection (the per- spective centres of each gable end). This is done to demon- strate to the student that the mode of finding the points of the gables by means of the two vanishing points s and t produces the same result as that of finding them by means of the diagonal lines ; the perpendicular lines drawn from the intersections of the diagonals passing directly through the points of the gables found by the vanishing points s and t. Problem IV. — In a note in a former part of this work we drew the attention of the student to the advantage he would find from using the diagonal lines. In sketching from nature, it is rarely possible — neither is it necessary — to have the actual measurement of the objects to be represented ; most of the relative proportions of one object with another must depend on the eye of the artist ; but if the position and form of any one object be carefully drawn on one part of the face of a building, the position and form of any similar object in a corresponding part may be found by means of the diago- nal lines. The skeleton of the house is drawn in the same manner as in the last problem and Prob. I. For the advan- tage of having the references distinct, the figure is drawn rather larger ; in consequence of which the vanishing points are out of the picture, but they are referred to in the first and third problems as G and H ; and the student in making his drawing must necessarily have them. The points to which the figures referred in the former problems, being un- necessary for our present purpose, are not marked ; and the references by figures here given relate only to the new rule about to be explained. The student must first, as before described (Prob. I.), PERSPECTIVE FOR STUDENTS. 29 draw all the lines of the house, with their letters A b, &c. for reference, up to the letter q, marking the respective vanishing points of each side, G and h. This done, he must sketch the position and size of the first window on the gahle end of the house, and then with his T square draw correctly the lines 1 and 2, carrying them a little above and below the lines he has sketched for the top and bottom of the window. Now in order to get the relative distance of the second window from the line E that the first window is from the line a, it is necessary, from the point 3, where the line 1 intersects the diagonal line L, to draw a line to the vanishing point g. This line intersects the other diagonal line M at 4 : and through this point of intersection 4 draw a perpendicular line 5. The point 4 on the diagonal m cor- responds with the point 3 on the diagonal l, and the line 5 drawn through it is at the same relative distance from the line E that the line 1 of the first window is from the line A. To find the relative perspective width of the second window, from the point 6, where the line 2 of the first window inter- sects the diagonal l, another line must be drawn to the vanishing point G : and the point where it intersects the dia- gonal m at 7 corresponds with the point 6 on the diagonal l ; through this point 7 another perpendicular line (8) must be drawn, which corresponds with the line 2 of the first window, and the space between the lines 5 and 8 represents, relatively to its perspective distance, the same as that between the lines 1 and 2. The ruler must now be placed on the line 1, at that point denoting the top line of the window, as a 9, and from it a line must be ruled to the vanishing point G : this will correct the original sketched line of the first window; and when it passes between the lines 8 and 5 it will represent the top line of the second window. The ruler must now be placed at the point on the line 1, that denotes the position of the bottom line of the window ; and from that point a line drawn to the vanishing point g will give, where it passes be- tween the lines 1 and 2, the bottom line of the first window, 30 PERSPECTIVE FOR STUDENTS. and where it passes between the lines 8 and 5, the bottom line of the second. In the first window, just drawn, the perpendicular lines forming the sides intersect the diagonal line L, as at 3 and (i ; and consequently the corresponding points on the diagonal line M are found easily, by ruling at once from these points to the vanishing point G. But it happens sometimes that the windows are so situated on the face of a building, that their sides neither intersect nor touch the diagonal lines. In order to point out the mode of proceeding when the windows are so situated, we will take the other side of the building. We will suppose a window to be in the situation of that represented in the engraving near the line a, between that line and f : this being sketched, the diagonal lines w and x must be drawn. The student will here perceive that neither of the upright lines of this window touch the diagonal lines ; the student must therefore with his T square, continue them upwards till they meet the diagonal line x at the points 11 and 12, and from each of these points draw a line to the vanishing point H. Where the upper line intersects the diagonal line w at 13, is a point corresponding with the point 11 on the diagonal line x ; and where the lower line intersects the diagonal line w at 14, is the point corresponding with the point 12 on the diagonal line x. From each of these points (13 and 14; a perpendicular line must be drawn downwards; and the space between these two lines represents the perspec- tive width of the second window, at its perspective distance from the line F, corresponding with the distance of the first window, from the line A. The upper and lower lines of the second window are found, as on the other side of the house, by continuing the lines of the top and bottom of the first window to the vanishing point H. Let us now suppose that on the roof there are two garret windows, situated immediately over the two windows just drawn, of the same width, and each window having a pointed roof. To find their width and position, the upright lines of PERSPECTIVE FOR STUDENTS. 31 the windows just drawn must be continued up through the line d, which will form their sides. Let any point on the nearest of these upright lines be chosen, as at 15, to fix their height (the mode for getting a fixed height would be the same as that explained foi getting the height of the gables, Problem I. 8, o), and from it rule a line to the vanishing point H ; this, crossing the upright lines already drawn, will give the rectangular parallelograms of the garret windows in perspective : and as there are only two garret windows, and consequently only two pointed roofs, to be drawn, the readiest way will be to find the situation of the points by raising perpendicular lines from the intersection of the dia- gonal lines of each parallelogram. The pointed roofs of these two windows are here drawn, and the lines used for finding them left ; but it would be quite superfluous again to go over the explanation of drawing them. In order to find the side of the first garret window, it is necessary first to draw a line from the point of the gable to the vanishing point G, as also from the point 1 5 to the same vanishing point, which lines will represent the perspective direction of the upper and lower lines of the roof of the garret window, — and which, the student must understand, in the real object are parallel to the horizontal lines on the gable side of the house. To find the points where these two lines terminate on the roof of the house, will reouire a little attention : the rule is similar to that employed for finding the directions of the gable in Problem III. The student must first find the vanishing point for the line p of the gable of the house. The lines of each of the sides of these windows, where they touch the roof, are in reality parallel to the line P of the gable (because the whole side of the roof is a uniform slope), and must con- sequently vanish to the same point ; therefore, from the point 16*, where the upright line of the window touches the lower line of the roof of the house, a line must be drawn to the vanishing point s ; and where this line intersects that drawn from the point 15 to the vanishing point g at 17, is the point 32 PERSPECTIVE FOR STUDENTS. marking the spot where the lower line of the roof of the garret window touches the sloping roof of the house. To find the point where the upper line of the roof of the garret window touches the sloping roof of the house, is a little complicated ; and to render it quite clear, an additional figure is introduced. Fig. 2 is drawn up to the point marked 17 of Fig. 1. The window here drawn contains the lines of both sides, as if it were transparent. The student will observe that the point of the front of the gable comes directly on a line, exactly mid- way (perspectively) between the two sides ; consequently, the point at the back must come on a line midway between the sloping lines on the roof forming the two sides ; from the points 3 and 1, two lines have been drawn towards the van- ishing point s. Where the line drawn from the point 3 meets the line drawn from the point of the gable 5 to the vanishing point G at 6, is the point where the two sides of the roof join ; and a line drawn from the point 6 to 4 will complete the drawing of the first garret window. The student will observe, that where the line drawn from the point 1 to the vanishing point s intersects the line drawn from the point 7 to the vanishing point g at 8, the lines forming the triangle 1, 7, 8, represent the farther side of the window, and correspond with the lines forming the triangle 2, 9, 4, the near side ; the lines forming the triangle 4, 8, 6, represent the form of the gable on the sloping roof of the house, and correspond with the lines forming the triangle 7, 5, 9. The garret windows in the drawing (Fig. 1) must now be com- pleted, in the manner described in Fig. 2 ; and the highest line of the roof of the house, u, with the extreme line of the slope, v, drawn to their respective points, as in the preceding problem (III.) ; and this figure will be finished. The rules given in this and the preceding plate will be found useful for drawing the divisions of tiles or slates on the roof. In Fig. 3, that portion only of the drawing of the house is introduced necessary for the purpose. The lines a, c, D, f, p ? u, v, are drawn as before described. From PERSPECTIVE FOR STUDENTS. 33 the point of the gable a horizontal line must be drawn to the left, to represent the geometrical length of the perspective line u ; this geometrical line must be divided into as many equal parts as there are tiles in each row, and a point of dis- tance found, to give the perspective positions of these several divisions on the line u. These being found, a line must be drawn through each from the vanishing point s to the line D, which will give the correct perspective direction of the divi- sions of the tiles or slates. From the point a, a horizontal line must be drawn to the right, to represent the geometrical length of the near half of the line c ; and this geometrical line must be divided into as many equal parts as there are rows of tiles on the roof, and a point of distance found to get the perspective positions of these points on the near half of the line c. These divisions, however, are required on the line P, and from each point of intersection on c a perpendi- cular must be drawn till it touch the line p, and from each point of contact a line must be drawn to the vanishing point H, which, by their intersections with the lines drawn between u and d, give the relative forms and positions of the different tiles ; as the lines crossing each other in Prob. II. represent the 64 squares of the chess-board. The tiles may be of various forms ; but we do not attempt to do more at present than point out the mode of rinding the perspective distances. The student may easily, on these, draw any form of tile that may happen to have been used, as in the example just given. The rules employed in this problem will be found ex- tremely useful ; the positions of all the objects in Fig. 1 are found without the necessity for using a point of distance, the diagonal lines answering for that purpose : they produce equal correctness, and save time and labour. The rule for finding the triangle 8, 6, 4, in Fig. 2, will be found useful in drawing roofs of buildings, where the pointed ends slope back as well as the sides ; a mode of construction very com- mon in old buildings, especially abroad, and not unfrequently met with in the roofs of country churches. c 3 34 PERSPECTIVE FOR STUDENTS. Before proceeding to the following pages, the author strongly recommends the student to choose certain familiar articles composed of straight lines, and endeavour to put them in perspective, according to the rules already explained. CHAPTER III. It is now necessary to advance a step farther. We trust the directions for drawing the foregoing problems will be found sufficiently clear to enable the young student to draw the superficies of any object of simple form represented by straight lines : thicknesses, such as the width of objects, like windows', doors, &c, have been purposely omitted in the preceding problems. The rules for drawing these thicknesses are the same as those employed in drawing the superficial forms, but demand a considerable number of additional lines ; these would tend seriously to embarrass the student, from their complication : it is therefore thought advisable to postpone this portion of our work, till the reader, by gradually accustoming himself to this mechanical draw- ing, will be less liable to become perplexed with a multi- plicity of lines. We will therefore proceed with some rules necessary for drawing curves in perspective ; and, as the most simple, we will commence with the circle. Let us suppose that a series of semicircular arches were to be drawn in perspective. We trust that the reader has so far profited by the foregoing examples, that he would have no difficulty in finding the width of each arch, the width of each column, pilaster, or pier between the arches, and their gradations of height. All this can be accomplished by the use of a common ruler, because it can be done by means of straight lines : but no ruler has yet been invented that will enable the student to draw the changes of forms taken by curves in perspective. The mode of proceeding is, first to draw geometrically the curve intended to be represented in page, 2>5 PERSPECTIVE FOR STUDENTS. 35 perspective, and through this geometrical figure to draw in certain directions various straight lines, that shall intersect or touch one another in certain points of the curve ; to put these straight lines in perspective which will change the relative positions of the various points, and through them, by hand, to draw the curve in perspective. In this Fig. 19. diagram (Fig. 19) for instance, we have a circle drawn ; and in order to find certain points in this circle, that will enable us to put it in perspective, it is enclosed in a square; and the student will perceive that the circle touches at four points of this square, exactly at the points of contact of the two cross lines. Nothing can be more simple than to put the six straight lines of this diagram in perspective ; which, when done, would furnish four points through which the curve line forming the circle in perspec- tive must be drawn. But four points are not found sufficient for the representation of a circle in perspective ; we must therefore find some additional points, by adding Fig. 20. to the straight lines already drawn, two diagonal lines (Fig. 20). The student will here observe that these diagonal lines intersect the line of the circle at four other points, exactly midway between those in the former diagram. Let us now proceed to construct the figure. Problem V. — The student ought now, without assistance, to be able to put in perspective the square, the diagonal lines, and the perpendicular and horizontal lines that pass through the centre ; but that no error may by possibility occur, we will give him a little aid. First, below the ground line, of any size that may be required, he must construct a geome- trical figure similar to the second diagram given in the preceding paragraph, and taking the upper line of the square of this diagram for his first line, draw the square in per- spective;* then from the opposite corners draw the two diagonal lines : from the point 1 draw a line to the vanishing * By referring to the drawing of the chess-board, Problem II., the manner of drawing the square in perspective will be found. 36 PERSPECTIVE FOR STUDENTS. point, and through the centre of the square (where the diagonal lines intersect) draw a horizonual line across, from the line d to the line e, to the points 4 and 2. The student will here perceive that he has put in perspective the straight lines contained in the second diagram above, and found the four points contained in the first : viz. the points marked 1, 2, 3, 4 of the geometrical drawing here given. It was observed, in the foregoing paragraph, that certain straight lines must be drawn, that shall intersect or touch one another at certain points of the curve, &c. Now the student will perceive that the diagonal lines drawn in the second diagram, though they intersect the line of the circle, have no points of intersection with any other straight lines, and that therefore these diagonal lines in the perspective drawing in this stage are quite useless : in order, therefore, to find the points where the diagonal lines intersect the circle, we must have two additional straight lines. In the square of the geome- trical drawing on each side, through the points where the diagonals intersect the circle, draw a line running from the top to the bottom line of the square, as the line A passing through the points 6 and 7, and touching the bottom line of the perspective square at 9, and the line B passing through the points 5 and 8, and touching the bottom line of the per- spective square at 10. From each of these points 9 and 10 a line must be drawn to the vanishing point ; and where the line drawn from the point 9 intersects the first diagonal, it gives a point corresponding with the point 6 in the geome- trical drawing ; where it intersects the second diagonal line, it gives a point corresponding with the point 7. In like manner the line drawn to the vanishing point from the point 10, at its intersections with the diagonal lines, gives two points corresponding with the points 5 and 8 of the geome- trical drawing. The perspective positions of the whole of the eight points being thus found, the student must carefully draw the curve to represent the circle, touching the points 1, 2, 3, 4, and PERSPECTIVE FOR STUDENTS. 37 passing through the points 5, 6, 7, 8. This mode is generally found sufficient for all ordinary purposes ; but where circles are required to be drawn in perspective of very large di- mensions, more points of intersection may be found in the geometrical drawing : these do not at all increase the diffi- culty, on the contrary, the curve line is drawn with more ease and accuracy ; but the multiplicity of lines would be apt to puzzle the student, and, as we before remarked, the fore- going is quite sufficient for all ordinary purposes. Let us suppose that the circle just drawn represents the spot on which a column is to be erected, and that a row of these columns is to be built; that the columns are to be distant from each other exactly their own width, and that the circle is marked on each spot where a column is to be erected. In order to represent this in perspective, it is first necessary to find a point of distance : this must be done by the same rule employed in Problem II. (the finding the point g). The student must first find the proper distance for, and afterwards draw, the perspective square in which the circle is to be drawn. To find the distance, he must measure off on the ground line, and on the opposite side to where he has fixed his point of distance, two spaces of the width of the geometrical square ; and from each point of division, 1 1 and 12, a line must be drawn to the point of distance c. Where the line drawn from the point 1 1 intersects the line D at 13, it gives the perspective distance between the two circles; and where the line drawn from the point 12 inter- sects the line d at 14, the space between that point and the point 13 represents the left side of the square in perspective in which the second circle is to be drawn. From the points 13 and 14 two horizontal lines must be drawn to touch the line E at the points 15 and 16. These two lines, with the portions of the lines d and e between their extremi- ties, form the four sides of the. square in perspective in which the second circle is to be drawn. From the points 13 to 16 and 14 to 15 draw two diagonal lines, and through their 38 PERSPECTIVE FOR STUDENTS. points of intersection draw a horizontal line between the lines D and E. The line running from the point 1 of the first square, in passing through the bottom and top lines of the second, gives the points corresponding to the points 1 and 3 in the first. The line running from the point 9 of the first square, where it intersects the diagonals of the second, gives the points corresponding with the points 6 and 7 of the first : in like manner, the line running from the point 10, at its intersections with the diagonal lines of the second square, gives the points corresponding with those marked 5 and 8 in the first ; and the horizontal line passing through the centre of the second square, gives, at its points of contact with the lines D and e, points corresponding with the points 4 and 2 in the first. The whole of the eight points being thus found in the second square, it remains only, as before described, to draw the curve line through them, which will represent the perspective position and form where the base of the second column is to be placed. By continuing in this manner, a third, fourth, or any number of circles may be drawn at their perspective distances : the two given are quite sufficient to illustrate the rule. It may here be well to remark, that every circle correctly drawn in perspective forms a perfect ellipse, whether, from the position from which it is viewed, it appear broad or narrow. By those who understand perspective but imper- fectly, this is frequently denied : and their disbelief arises from their mistaking the middle horizontal line for the axis of the ellipse, whereas it simply divides the circle into its perspective halves. If all the lines serving to draw the curve were to be erased, and the curve left ; if its proper axis (a long straight line, that divides it longitudinally into two equal parts,) were to be found, it would show that the curve forms a true ellipse. Problem VI. — By the applipation of the same rule as that explained in the foregoing problem, with a little variation in the manner of employing it, an arcade or succession of I if 4 PERSPECTIVE FOR STUDENTS. 39 arches may be put in perspective ; a small geometrical draw- ing (g d) or elevation of which is placed at the side of the problem, and is drawn to a scale of one-fourth of the per- spective drawing. Let the student first draw an elevation similar to the one in the plate, of one-fourth the size he intends to make his perspective drawing; and then let him draw the perpendi- cular line a by measurement from it, and at the supposed height of a figure (or his eye from the ground line) draw the horizontal line across his picture. To the best of the judg- ment of the artist, from the point 1 (the top of the line a) let him sketch the perspective inclination of the line B, and con- tinue it till it meet the horizontal line : the point at which it touches will be the vanishing point. From the point 2 (the bottom of the line a) the line c must also be drawn to the vanishing point. These two lines B and c represent the per- spective directions of the upper and lower lines of the struc- ture. The student will find, by reference to the geometrical drawing, that the height of each arch is three-quarters the height of the whole structure ; the width of each arch, one- fourth ; and the width of each pier, between the arches, one- eighth of the height of the stiucture. If the student mark off, on the line a, three-fourths of its length from the point 2, as at the point 3, it will mark the real geometrical height of the arch ; and from this point 3, if he rule a line, D, to the vanishing point, it will determine the height of the respective arches as they recede from him The perspective distances — that is, the perspective width of the piers and arches — may be found on the line B by the sume rule as that employed for finding the position and width of the windows in Problem L* A long horizontal line (e) must be drawn from, and to the * They might be found with equal correctness on the line c, from the ground line, by employing the rule given in Problem II. for finding the squares of the chess-board. Two lines are drawn from similar distances on the ground line to those on the line e, to show that the points of inter- section are the same. 40 PERSPECTIVE FOR STUDENTS. left of the point 1, to represent the geometrical line of the top of the structure, and on it must be marked the geometrical width of the several piers and arches ; as from 1 to 4, the geometrical width of the first pier (one-eighth of the line a) ; from 4 to 5, the width of the first arch (one-fourth of the line a). The student should now, if he were sketching from nature, draw lightly with his pencil the first arch by eye, or mark, as at the point 6 (on b), the distance of the nearest side of the arch to the line A ; and through this point rule a line from the point 4 till it meet the horizontal line ; its point of contact will be the point of distance. From the point 5 a line must also be drawn to the point of distance, intersecting the line b at 7. These two points, 6 and 7, corresponding on the perspective line B with the points 4 and 5 on the geometrical line E, give the perspective width of the first pier and arch ; and from each of them a perpendicular line must be drawn till it meet the line c. These two lines cor- respond with the lines a and b in the elevation g d. The student will observe that the arches are all formed of semicircles ; consequently, he will only have to construct semicircles for finding the points for the curve on the geo- metrical line E ; therefore on this line, placing one point of the compasses at 8, from the points 4 to 5 describe a half- circle ; from the points 4 and 5 draw upwards two perpendi- cular lines, and parallel to the line E, so as just to touch the top of the semicircle,* a line meeting the two perpendiculars at the points 9 and 10. The semicircle will thus be enclosed in a half- square. From the point 8 a line must be drawn to each of the corners 9 and 10 ; and through the points where these lines (which represent the upper halves of two diagonal lines) intersect the semicircle, two perpendicular lines must be drawn to touch the line e at 11 and 12 : if the student now draw a perpendicular line from the point 8 till it meet the top of the semicircle, he will perceive, by comparing it with the * Straight lines touching a curve in this manner are called tangents. PERSPECTIVE FOR STUDENTS. 41 preceding problem, that lie has drawn the upper half of the geometrical figure there represented for drawing a whole circle. The line d being that which regulates the height of the several arches, the points 13 and 14, given by the intersec- tions on it from the perpendicular lines drawn from 6 and 7, represent the perspective position of the points 9 and 10 of the geometrical drawing : the points 4 and 5 must now be found, for which purpose the geometrical height of the half- circle must be set on the line A below the point 3 (respresent- ing the height of the top of the arch), as at 15 ; and from this point rule a line to the vanishing point. Where this line intersects the perpendicular lines at 16 and IT, drawn from the points 6 and 7, are the points corresponding with 4 and 5 of the goometrical drawing on e. To find the points 11, 8, 12 on e in the perspective drawing, a line must be drawn from each of them to the distance point ; and from their points of intersection on the line b, perpendicular lines must he drawn to the line F at 18, 19, 20, which are the perspec- tive positions of the points 11, 8, and 12. From the point 19 to each of the corners 13 and 14 a line must be drawn, which will complete the perspective drawing of the straight lines in the geometrical figure erected on the line e. The curve must be drawn as in the former problem, through the points corresponding with those of the geometrical elevation. To continue the line of arches, another space of one-eighth of the line a must be measured off on the line e, for the width of the second pier, and beyond that a space of one- fourth of a, for the width of the second arch, as from 5 to 21, and from 21 to 22. From these points, lines must be ruled to the point of distance, and the sides of the second arch (c d of the geometrical drawing) must be drawn on the perspective drawing, in the same manner as the sides a b of the first arch. To find the points between 21 and 22 (23, 24, 25), corresponding with the points 11, 8, and 12, between 4 and 5, it is not necessary again to construct a geometrical figure, similar to the one for finding the points for the first 42 PERSPECTIVE FOR STUDENTS. arch, because the space between 21 and 22 being exactly the same as that between 4 and 5, these corresponding points must come at precisely the same distance from each other, and may therefore be measured off with a pair of compasses, the points of the geometrical distances for the second arch (on e) corresponding with the points of the first, thus : T2-> ih ih ?V ^he mode of drawing the second and fol- lowing arches in perspective is precisely similar to that em- ployed for drawing the first: in the example given, all the lines necessary for drawing the second arch are introduced, but with- out the references. The three remaining arches are drawn, but the lines used for finding them are purposely omitted. There is another mode of applying this rule, equally correct, which it is desirable for the student to understand. The lines A, B, D, E, and F (Fig. 2) must be drawn as in the preceding example (Fig. 1). The lines d and f being drawn, the points 3 and 15 must have been found ; let that portion of the line A between the points 3 and 15 form the left side of a half-square, similar to the side 5, 10, of the one erected on the line e, Fig. 1, and upon this line construct a half- square of the same dimensions as that on E, and describe within it a semicircle. From the centre point draw to the two upper corners lines corresponding with the lines 8, 9, and 8, 10 ; and from the same centre point draw a perpen- dicular line to touch the top of the half-circle, and you will then have a geometrical figure similar to the upper half of the second diagram in the introduction to Part III. The variation in applying this rule consists in the mode of finding the points of intersection of the diagonal lines with the curve. In placing the geometrical drawing at the side of the line a, instead of on the line e, it is necessary for finding these points in perspective (marked a and b in Fig. 2), to draw through them a horizontal line to touch the side (as at c), instead of two perpendicular lines to give the points at the bottom of the half-square ; and from this point c, a line (g) must be drawn to the vanishing point. The points PERSPECTIVE FOR STUDENTS. 43 13 and 14, and 16 and 17, are found as in Fig. 1 ; and the student must now find, by drawing a perpendicular line dividing the arch into its perspective halves,* the point cor- responding with the point 19 of Fig. 1, and from it draw a line to each of the points 13 and 14. The line g, where it intersects the diagonal lines of the half-square in perspective, will give the points corresponding to the points a b in the plan at the side, through which to draw the curve, and in its possage towards the vanishing point would give the corre- sponding point for every arch. In the example here given, those lines only are used that are absolutely necessary for the explanation of the rule ; the student will do well to draw the whole figure with the five arches on this plan. Problem VII. — The reader has, doubtless, at one period or another, been in some place where he has seen a row of arches straight before him, such as the Burlington Arcade, the side aisle of a church, &c. Let him suppose, then, that he is standing before a row of arches, and in such a position as that the point of sight (in this case, also the vanishing point,) be exactly in the middle, between the two sides of the arch. Fig. 1. The student must first draw the elevation of the first archway : this is so extremely simple, that it scarcely needs any directions. Having drawn the external lines, 6, £?, the ground line, and the horizontal line, draw the sides of the archway a and b, up to the points 1 and 3 (from where the curve springs), and draw a horizontal line between these two points : from the centre of this line, at the point 5, with a pair of compasses describe a semicircle from the points * The student, it is to be hoped, recollects that the centre of any rectangular parallelogram in perspective is found by the intersection of its diagonal lines. The figures 6, 7, 13, 14, represent the four corners of a rectangular parallelogram in perspective, as do also the figures 13, 14, 16, 17, and 6, 7, 16, 17. If the student, in any one of these, draw two diagonal lines, as from 7 to 13, and from 6 to 14, and through this point of intersection draw a perpendicular line to r, it will give the point (19) required. 44 PERSPECTIVE FOR STUDENTS. 1 and 3. From each of the points 1, 2, 3, 4, draw a line to the vanishing point.* The student must now on the line c (drawn from the point 1 to the vanishing point), mark the distance of the second arch from the first, as at 6, and from this point draw a perpendicular line till it touch the line d, at 7. From the line a, through the point 7, draw a horizontal line, till it touch the line b ; and from the point 8, where it intersects the line F, draw a perpendicular line to meet the line e at 9. The points 6, 7, 8, 9, are the points of the second archway, cor- responding with the points 1, 2, 3, 4 of the first. Draw a horizontal line between the points 6 and 9 ; and from the point 5 draw a line to the vanishing point : where this line intersects the line 6 to 9 just drawn, at 10, with a pair of compasses open to the distance of from 10 to 6, or 10 to 9, which are equal, describe another half-circle ; this completes the second archway. We will suppose the archways to be equidistant from each other, and that the distance between each is a space equal to from a to b. In order to find the relative distance the third arch appears from the second that the second appears from the first, we must find the point of distance, which may be found in a similar manner to that employed in the Problems II. and Y. From the point 4, passing through the point 7, a line must be drawn till it meet the horizontal line ; the point of contact is the point of distance. To the right hand, from the point 4, two spaces must be measured off on the ground line, each equal to the space between A and b, as at 1 1 and 12 ; from each of these points a line must be ruled to the point of distance, and where they intersect the line D they give the points determining the perspective distances of the third from the second arch at 13, and the fourth from the third at 14. The mode of drawing the third archway is similar to that employed for the second, with this difference only, that the perpendicular line must be drawn up from the * This point has already been settled to be placed midway between the two sides of the arch. page 45. PERSPECTIVE FOR STUDENTS. 45 point 13 on d to the line c ; whereas the second arch was commenced by drawing a perpendicular line down from the point 6 on c to the line D. To draw the third archway, raise a perpendicular line from the point 13 till it meet the line c at 15 ; from 15 draw a horizontal line till it meet the line E at 16; from 16 draw down a perpendicular line to meet the line f at 17; draw a horizontal line between 15 and 16, and from the point midway between them describe a third semicircle ; this completes the third archway. The fourth is drawn in a similar manner, commencing at the point 14 ; and a fifth, sixth, or indefinite number, may be con- tinued by the same rule. If, however, instead of being placed exactly in the middle, between the two sides A B of the archway, the spectator had placed himself a little on one side — as opposite the point marked g on the horizontal line, the arches would have had a very different appearance. Viewed from this position, more of the left side of the inner archways would be visible, and the right side of the first archway would entirely exclude the view of the right side of the inner ones. The appearance of the archways, as seen from this position, would be as represented in Fig. 2. In this example there are neither letters nor figures of reference : the mode of drawing it is exactly similar to that employed in Fig. 1, the position of the vanishing point only being altered. The student will observe that the right side of all the inner arches is hidden by the first, and that a por- tion only of their semicircles is seen ; nevertheless, it is best to complete each archway in the drawing, to insure correct- ness ; and this would be more necessary if it were drawn in oblique instead of parallel perspective. A few of the lines are left, to assist the student in his drawing the figure. Fig. 3 we shall have to consider in a more advanced part of the work. Problem VIII. — In the introductory portion of this work, it will be recollected that some observations were 4G PERSPECTIVE FOR STUDENTS. made respecting circular objects ; and the various forms tbey took, according to the positions from which they were seen, was familiarly explained by the example of a common bowl. It has already been remarked, that all perspective represen- tations of circles form perfect ellipses ; * but the width of these ellipses varies according to the distance the circular form is placed above or below the eye of the spectator. To illustrate this, a column, composed of five distinct pieces, is chosen, and the spectator is supposed to view it from such a position as to bring the vanishing point (f) exactly in the centre of the column, and midway between the top and bot- tom. The student will understand that the joints of a circu- lar column are circular, like the top and bottom, and that the forms of the curves of the joints vary in appearance accord- ing to their distance above or below the eye of the spectator. The student will observe that the curve or ellipse a, the base of the column, from being at the greatest .distance below the eye, is much broader than the curve B, representing the first joint ; that the second joint of the column c, from its being exactly level with the eye, forms only a straight line ; for if the student imagine, that instead of this joint he had before him a thin circular plate, from its being exactly level with his eye, it would be impossible to see either its upper or lower surface, and consequently could only be represented by a straight line. The curve D, from being the same height above the eye that the curve b is below it, forms a precisely similar ellipse ; and, for the same reason, the ellipses a and e are also similar : this the student will readily perceive by turning the example upside down. The curves d and - e, from being above the eye, show the upper half of the curve; the curves B and A, from being below the eye, show the lower half. In order that the student may fully comprehend the draw- * The only exception is where the curve comes, as in the joint c of this figure, exactly on a level with the eye of the spectator, in which case st is represented by a straight line. PERSPECTIVE FOR STUDENTS. 4? ing of this problem, let him cut five square pieces of card, and draw on the face of each of them a figure similar to the diagram represented in the plate ; and through each card, at the points tf, 5, c, and 1, 2, 3, 4, 5 } 6, 7, 8, pierce a hole, as also through the point at the centre. This done, let him place the cards one over another, so that the various points of each card shall lie under and over the corresponding points of the others. In this position of the cards, let him put a piece of stick or wire, the length of the column, through the centre holes, and separate the cards on this stick to an equal distance one from another, always keeping the corresponding points on the cards in the same relative position. If the student were now to put a straight piece of wire (a common knitting-needle will answer the purpose) through any one of the points of the top cards, and holding it perpendicular, were to push it downwards, it would pass through the corresponding holes in the four cards underneath. By clearly understanding this, the student will find his progress through the problem greatly facilitated. The student must first draw the square, and find the points in perspective, corresponding to the points in the diagram, for drawing the curve of the base of the column. This is fully explained in Problem V., with this slight variation, that the vanishing point in this drawing is placed in the middle of the object to be represented, instead of at the side : this done, he must letter and figure the several points to correspond with the letters and figures on the points in the diagram, as the points a, c, 6?, 1, 2, 3, 4, 5, 6, 7, 8. From the points d and c draw two perpendicular lines, g and h, each four times the height of the side of the square of the diagram, marking on each line the divisions of each fourth, as at the several points marked c and d* and draw * The student must understand that the same figures and small letters are employed as references for the corresponding points in each of the squares, and that the several squares, with their first line and the 48 PERSPECTIVE FOR STUDENTS. a horizontal line between the lines g and H, from each point, c to up to the toi). The first three of these horizontal lines, b, c, and d, represent the first line of the three squares in which the curves to represent the joints are to be drawn : the fourth line, E, represents the first line of the square in which the curve to represent the top of the column is to be drawn. From each of the points c d, the extremities of the lines b, d, e, a line must be drawn to the vanishing point F, as the lines J, K, l, m, n, o.* By reference to the cards, in the position before described, the student will perceive that the circles drawn on them are in a similar position to that of the top and bottom, and the three joints of the column ; and that a perpendicular line passing through any one of the points, representing certain points in the circle on the top card, would pass through the corresponding points in the cards beneath. So is it in the perspective drawing ; the corresponding points in the several perspective squares lie exactly one over the other, and will be found by means of perpendicular lines. From the point a of the first square a, a perpendicular line P must be drawn till it meet the line J of the square e at a ; and from the point b of the square A, a perpendicular line r must be drawn till it meet the line k of the square e at b ; by drawing a horizontal line between these two points a and b (square e), the square E will be completed. The student must here understand that the several lines J, L, and N, drawn from the points d to the vanishing point, represent the perspective directions in each of the squares B, D, and e, of the line d — a of the diagram ; and that the line P is the perspective representation of the wire passing through curve drawn within them, are alike designated by their respective letters, a, b, c, D, E. * The middle joint c being represented by a straight line, no points can be required on it. It will only be necessary to determine its per- spective width, which will be done in determining the width of the oth«r curves. PERSPECTIVE FOR STUDENTS. 49 the points a of the cards : consequently, where the line p intersects the lines n, l, and J, it gives the perspective posi- tions of the points a in the several squares b, d, and e. In like manner the lines K, m, o, running from the point c to the vanishing point, represent the perspective directions in each of the squares of the line c — b of the diagram ; and the line R is the perspective representation of the wire passing through the several points b of the cards : consequently, the points at which this line intersects the lines K, m, and o, are the perspective positions of the several points b in the respec- tive squares b, d, and e. The student must now draw a horizontal line from the points a to 6, in each of the squares B and D ; and then, in each of the three squares b, d, e, he must draw the diagonal lines from the points d to and from a to c. From the point 7 (square a), the point designating the extremity of the perspective circle to the left, a perpendicular line s must be drawn till it meet the line J (square e) ; and from the point 3, the extremity of the perspective circle on the right, a perpendicular line t must be drawn to meet the line K (square e). These lines s and t, represent the two sides of the column, and are the perspective delineation of the wires passing through the holes 7 and 3 of the cards : conse- quently, where the line s intersects the lines representing in perspective the line d — a of the diagram (those portions of the lines J, L, and n, between the letters d and a), it gives the perspective positions of the points 7 in the respective squares B, D, and e. In like manner, where the line t intersects those portions of the lines k, m, o, between the letters c and b (representing the line of the diagram c — b in perspective), it gives the perspective positions of the point 3 in the respective squares B, D, and E. The student must now, from the point 5 of the square A, draw a perpendicular line u, till it touch the top line of the square e ; and this line, from the spectator being placed exactly in the centre of the column, will answer for a per- . Perspective* D 50 PERSPECTIVE FOR STUDENTS. pendicular line that should be drawn from the point 1, square A, till it touch the further line of the square E. This line u, then, represents in perspective the wires passing through the holes 5 and 1 of the cards, and designates at its intersections on the first line of each square the point corresponding with the point 5 of the diagram ; and at its intersections with the further line of each square it designates the positions of the points corresponding with the points 1 of the diagram. The student will perceive that he has now, in each of the perspective squares, points for drawing the curves cor- responding with the points 1, 3, 5, ? of the diagram ; he must now find the remaining points, 2, 4, 6, 8, in each of the squares. From the point 6 on the diagonal line d — 5, square A, a perpendicular line v must be drawn, till it touch the diago- nal line d — 5, square e. This line v represents in perspec- tive the wire passing through the holes 6 of the five cards ; and where it intersects the several diagonal lines d — in the respective squares b, d, e, will be a point corresponding to the point 6 in the diagram. In like manner, from the point 4 on the diagonal line c — square A, a perpendicular line x must be raised, till it meet the diagonal line c — «, square e. This line x representing the wire passing through the points 4 of the cards, will give, at its intersections on each of the diagonal lines c — a point corresponding with the point 4 on the diagram. Similar to the preceding perpendicular lines v and x, the two others, Y and z, must be drawn from the points 8 and 2 on the diagonal lines c — a and d — square A, to meet the corresponding diagonal lines c — a and d — 5, square e ; these will give the perspective repre- sentations of the wires passing through the holes 8 and 2 of the five cards. Where the line Y intersects the diagonal lines d — b of the several squares, will be found the points corre- sponding with the point 2 of the diagram ; and where the line z intersects the diagonal lines c — a of the several squares, will be the points corresponding with the point 8 of the PERSPECTIVE FOR STUDENTS. 51 diagram. The whole of the perspective positions of the points of the diagram being found in each perspective square, the student, as in Prob. V., must draw the curve in each, through the several points 1, 2, 3, 4, 5, 6, 7, 8, which will complete the perspective drawing. This problem, though not difficult, requires attention, from its being a little more intricate than any preceding ; but, with the assistance of the cards, the author thinks it barely possible for the intelligent student to fail understand- ing it. Problem IX. — In sketching from nature, the artist has frequently to represent, and in old buildings especially, doors, windows, arches, &c. of a pointed form, commonly called gothic arches, gothic windows, &c. The curves of these pointed arches are formed in geometrical drawing by the intersections of segments of circles, Fig. 21. The pointed arch here drawn is Fig. 21. formed by the intersection of two semi- circles ; and by the rules already explained, the student would be able easily to put it in perspective ; as by putting the two semicircles in perspec- tive, their intersection would give the pointed arch, which would be in perspective also. But these pointed arches vary so much in their proportions, some being extremely obtuse, whilst others are very pointed, that it is better to give a general rule by which pointed arches of any form may be put in perspective. At the side of the problem, an elevation of the building to be put in perspective is drawn, represent- ing a gothic arched doorway, with a gothic window on each side ; and, like the elevation in Problem VI., it is drawn to the scale of one-fourth of the perspective drawing : the student will therefore bear in mind, that in making for his perspective drawing geometrical measurements, they are understood to mean four times the size of that given, and marked g d. The whole of this figure, with the exception of the curves D 2 52 PERSPECTIVE FOR STUDENTS. of the doorway and windows, must be drawn in a similar manner to Prob. VI, The line A must first be drawn ; and across the picture, at the height of the spectators eye, the horizontal line ; then the line B, the perspective top line of the building, to the horizontal line, to fix the vanishing point ; and from the bottom of the line A, a line c to the van- ishing point, for the perspective base-line of the building. The point 3 on a, the geometrical height of the pointed top of the windows, must next be marked, and from it the line D drawn to the vanishing point, to regulate their perspective height. The line e must next be drawn, and on it the geo- metrical widths of the doorway, windows, and spaces be- tween must be marked, as at a, 6, c, 0,/, g ; a distance- point must next be found, to get the perspective positions of these points on the line b.* The distance-point having been found, and the perspective positions of the points a, c, d, 0, /, g marked on the line b, draw from each of these points a perpendicular line till it touch the line c. On the line e, between the points a and 5, construct a geometrical figure of the arch of the first window. This is done by fixing one point of the compasses at the point a, and opening them till the other point touches the point b; describe upward the segment of a circle, and then changing sides, and fixing the point of the compasses (at the same extension), at the point 6, describe another segment of a circle from the point a, till it join the one before drawn : this will give the geometrical drawing of the arch. From the points a and b draw up two perpendicular lines, and, just touching the point of intersection of the arch, draw a hori- zontal line to meet them at the points 4 and 5. From the * Throughout this problem the student must constantly refer to Prob. VI. Although the figures and letters vary, in this, from those used in the sixth problem, still the principle is the same; and it would occupy too much space to go over the same ground in every problem : moreover, by changing the references, and giving more general explanations, it will oblige the young student to exert his faculties. PERSPECTIVE FOR STUDENTS. 53 point of the arch draw down a perpendicular line to touch the line e at 6, and from the point 6 draw two lines to the corners 4 and 5. Through each of the points 7 and 8, where these lines intersect the curve lines, draw a perpendicular line to the line e, at 9 and 10, and a geometrical figure will be constructed, containing points that, put in perspective, will be a guide for drawing the curves. The perspective positions of the points 9, 6, 10 (on e) must be found on the line B, in a similar manner to the points 11, 8, 12, in Prob. VI. The line d, drawn from the point 3, regulates the per- spective height of the points of the arches ; and to find the perspective positions of the points from which the curves commence, their geometrical height must be marked on the line a, as at the point 11 ; and from this a line f must be drawn to the vanishing point : this line, where it intersects the perpendicular lines drawn from the points a and b (line b), gives the points corresponding to the points a and b of the geometrical drawing ; and where the line d intersects the same lines (drawn from a and 5, line b), it gives the points corresponding to the points 4 and 5 of the geometrical draw- ing. The perspective points 9, 6, 10, on the line b, must now be carried down by perpendicular lines to the line F, and from the point 6 (on f) two lines must be drawn to the corners 4 and 5 : this completes the perspective drawing of the straight lines of the geometrical figure, and through the corresponding points the curve must be drawn. The point 12 (the height of the bottom of the windows) must now be marked on a, and from it a line g drawn to the vanishing point : where this line o passes between the two perpendi- cular lines drawn from a and b (line b), representing the sides of the window, it gives the perspective line of the bottom of the window. The farther window is drawn in a precisely similar manner to the nearer one, finding the geo- metrical points on the line E, between e and /. All the lines necessary for drawing this second window are shown, but without references. 54 PERSPECTIVE FOR STUDENTS. The mode of drawing the doorway is similar to that used for representing the windows. The point 13, the geometrical height of the point of the arch, must be marked on a, and a line H drawn from it to the vanishing point, to fix its per- spective height, as the line D does that of the windows : and the point 14, the geometrical height of the points from which the curve lines commence, must also be marked on the line A, and from it a line J drawn to the vanish- ing point, to determine their perspective height, as the line f does those for the points where the curves of the windows commence. The geometrical form of the arch of the doorway must now be drawn on the line E, between c and — ■ f C h a D A 1 ¥ J n the perspective position of the point e of the original object ; where it intersects the visual ray g e it gives a point c, the perspective position of the point g in the original object. Where the perpendicular line from k intersects the visual ray / e, it gives the perspective position b of the point / of the original ; and the point of intersection with the visual ray h e gives a point d corresponding with h in the original object. Thus we have in the points abed the perspective positions of the four corners of the square A. Consequently, the perpendicular drawn from where it passes between the visual rays e e and g e, represents on the plane of deline- ation the line e g of the original object A ; that drawn from where it passes between the visual rays / e and h e, represents on the plane of delineation the line f h of the original object. By ruling lines from the points a to b and c to d, we have on the plane of delineation a form such as the object would take on a sheet of glass similarly placed, if the spectator were to trace on it the form he sees through it ; the relative positions of the three essentials for perspec- tive drawing being as described, — viz. the positions of the original object, the spectator, and the plane of delineation. Trusting that the matter in the preceding pages, which may be said to contain the groundwork from which the PERSPECTIVE FOR STUDENTS, 89 various modes of representing objects in perspective are deduced, is tolerably understood, we will first offer a few observations, and then proceed to practice. The foregoing may be summed up in very few words : — The rays of light, which are the cause of vision, are understood to proceed from every object in straight lines to the eye of the spec- tator, and in their transmission are supposed to pass through an imaginary plane, situated somewhere between the spec- tator and his subject. In order to make a perspective draw- ing, the points where the rays of light (visual rays) pass through this imaginary plane must be ascertained, these points transferred to the canvas or paper, and by means of these the form and size of the objects accurately delineated. The diagrams requisite have been made with as much atten- tion to simplicity as the subject admitted, and are intended solely to illustrate the principle, that correct representations of form are to be drawn by finding the above-mentioned points : various modes are employed for finding them, which it will be our endeavour to make thoroughly understood. The horizontal line on the plane of delineation selected for finding the perspective width of the square a (Figs. 11, 13, 14), is the base line, though the same result might be obtained by taking any other horizontal line. The base line is that usually chosen for this purpose ; and as it is unquestionably the most convenient, from the circumstance of draftsmen being furnished with a ground plan and elevations from which they are to execute the perspective drawing, it would only be perplexing the student to furnish him with examples and rules for what he may most probably never require. To avoid any errors, it may be well to remark that the ground plane, which is but another name for the surface on which the object to be drawn rests, is supposed always to be a flat even surface of great extent, and that the plane of delineation is always supposed to stand perpendicularly on it. Any devia- tion from this might materially affect the representation. 90 PERSPECTIVE FOR STUDENTS. CHAPTER III. Where a number of objects combined are required to be represented in perspective, to proceed by finding every point by means of intersecting points on the plane of delineation, would be an extremely tedious mode of procedure; and these points are used as sparingly as possible, the main object being to produce accuracy with the smallest possible number of lines. In order to make our illustrations clearly intel- ligible, and in the comparison of one mode with another, to show that we may arrive at the same result by various means, we are necessarily compelled to employ more lines than would be requisite for an ordinary drawing; but in doing so, we will endeavour to point out the best and readiest modes of proceeding. Vanishing points are what are com- monly used for determining the perspective heights of per- pendicular lines, as well as for regulating the length and direction of horizontal ones. It has already been explained in Part I. pp. 9, 10, Figs. 14, 15, that those lines in an ori- ginal object that are parallel, in the perspective representation incline towards each other and meet in a point, which is called the vanishing point : keeping this in mind, let us proceed to draw a plane figure in perspective from the following plan. Fig. 15, Plan. Let A represent the top of a table, perpendicularly over the PERSPECTIVE FOR STUDENTS. 91 edge of which, b, stands a sheet of glass ; let c represent the position of the spectator, and d a square figure lying flat on the table. We should here call A the ground plane, the upright sheet of glass over B the plane of delineation, and D the square figure to be represented, the original object viewed from the point c : * from these data it is required to draw the figure d in perspective ; the first step towards which will be to draw a parallelogram (Fig. 15, Rep. l)to represent the picture (efg h), and across the picture, parallel to the ground Fi S- 15 > Representation 1. line e F, at the height above H the ground line the spectators eye is above the ground plane, draw the horizontal line J (see Part I. pp. 5, 6, Fig. 6). Before proceeding with this drawing, it must be thoroughly e j, a j ' F understood that the line e f, the ground line in the representation, is in all respects similar to the line B of the plan, and that all points of intersection found on b are to be carried to ef; and moreover, that the parallelogram e f g h is the representation of the plane of delineation standing upon the line b. As in this case we propose to find the perspective positions of the points b c h j by means of a vanishing point, the position of this vanishing point must first be ascertained; and the vanishing point in this position of the square relative to the plane of delineation, will be the point of sight, which is always perpendicularly * Nothing can be more readily imagined than that the whole of this figure might be drawn from a description of the absolute measurements of the different objects ; as, for instance, we might say d to be twelve inches square, situated one foot from b ; b four feet long ; and c four feet perpendicularly distant from the point a on b ; the eye of the spectator two feet above the ground plane a. From such a description, a perspec- tive drawing may be made of any size, either large or small, by working from a scale of so much to a foot — either the eighth of an inch, or half a dozen yards. — jr— K 1 \ \ "/ c 1 \ 92 PERSPECTIVE FOR STUDENTS. opposite the spectators eye on the plane of delineation : * we must therefore mark on the base line of the plane of delineation, the point a perpendicularly opposite c ; carry this point to the ground line e f, and perpendicularly over it on the horizontal line, mark the point of sight at k. In order to find the length the line b c will appear, it is necessary to draw the visual rays b c and c c ; carry the points of intersection they make with the base of the plane of delineation d and e to the ground line E F, and from each draw a perpendicular line on the picture. From d to e will be the length the line b c would appear ; the point b will be found somewhere on the perpendicular drawn from d, and the point c on some part of that drawn from e. The lines b h and c j of the plan are parallel lines ; and though if they were continued to any extent they would never meet, yet in the representation they incline towards each other and meet in a point ; and being at a right angle with the plane of delineation, this point would be the point of sight. Continue the lines h b and j c up to the plane of delineation at / and g, and carry these points to the ground line E F, and from each point draw a line to the point K, the point to which the parallel lines f b h and g c j of the plan must incline (or any others that might be parallel with them) : the intersection of the line / K with the perpendicular from d, gives the perspective position of the point b of the plan ; the intersection of the line g K with the perpendicular from 0, gives the perspective position of the point c of the plan ; * The point of sight is always used as the vanishing point for lines that are situated at a right angle with the plane of delineation ; those lines that lie in a direction parallel to it have no vanishing point, but are represented by lines parallel to the ground line of the picture. This will be understood when we come to the rule for finding the positions of vanishing points in general ; it is necessary here to understand that all lines at a right angle with the plane of delineation do have their vanishing point in the point of sight, and that this point is on the plane of delineation perpendicularly opposite the spectator's eye (Part I. Plate I. A, Fig. 2). PERSPECTIVE FOR STUDENTS. 93 and a straight line drawn from one to the other, the repre- sentation of the line b c. The direction of the sides b h and c j are represented by the lines b k and c K ; and to determine their length, it is necessary to find the positions on them of the points h and j ; which is extremely simple. From the points h andy, draw the visual rays h c and j c ; carry the points of intersection Hon B to the ground line E F, and from each point draw a perpendicular line : where that drawn from k intersects the line / K is the perspective position of the point h ; and where that drawn from the point I intersects the line g k is the perspective position of the point / A line drawn from h to j completes the drawing, the figure b c j h being the perspective representation of the square d, viewed in the positions described. In the foregoing example more lines have been used than are absolutely required for drawing this figure, but they have been introduced for the more clearly exemplifying the mode for finding the positions of points, by means of a vanishing point and the visual rays; but the visual rays^ c and c c (in the plan) might have been omitted, and con- sequently the points and lines derived from them on the picture ; for, as is shown in the Second Representation, Fig. 15, having the lines / K and g k drawn, and the points b and h found by means of the intersections d and h of the Fig. 15, Representation 2. visual rays b c and h c, the H points c and j are found from the points b and h. The lines b c and h i in the plan, being parallel to the base of the plane of delineation, are represented in the drawing by lines parallel e to the ground line ; hence lines drawn parallel to the ground line from the points b and h to the line j K, give an eoualb* accurate reioresentation of the — dp K I 1 94 PERSPECTIVE FOR STUDENTS. figure in a more simple manner, and at a considerable saving of labour. In geometry, a point is defined to be that which has position but not magnitude, and a line to be length without breadth or thickness ; the extremities of lines are points, and the intersections of one line with another are also called points. Any straight line may be represented in perspective by finding the positions of its extremities, and any combi- nation of straight lines by finding the positions of the extremities of each separate line. Curves may be drawn in perspective by finding intersecting points in the original figure (Part I. pp. 35, 36), and finding the positions of these points on the plane of delineation. If then a drafts- man has the knowledge how to find any single given point, he will be able by the same means to find a second, third, or any quantity ; hence, straight lines may be drawn in per- spective by finding the position of their extremities, and curve lines by finding points of intersection, by understand- ing clearly how any single point is to be found. We will therefore proceed to show, first, how the perspective position of any single point is to be ascertained ; and afterwards, a combination of them : so that any plane figure may be put in perspective, upon the same principle employed for Fig. 16, Plan. A C B a c drawing the square, Fig. 15 ; as in the above-given plan, Fig. 16, from which it is required to find on the picture PERSPECTIVE FOR STUDENTS. 95 Fig. 16, Representation. E F \ the position of the point a, situated on b the ground plane, the relative positions of the plane of delineation and the spectator being as c and d, the eye of the spectator situated above the ground plane, the height shown by the horizontal line E (Fig. 16, Rep.). First, find the position of the point of sight (as in Fig. 15), by drawing the line a d perpendicular to c; draw the visual ray a d, inter- secting the base of the plane of delineation at b ; bring the point a perpendicularly forward to the plane of delineation at c,* and then carry these three points a b c to the ground line of the picture. From a draw a line perpendicular to the ground line, to the horizontal line at f ; this will be the point of sight ; also a perpendicular line across the picture from 5, on some part of which the point A will be found. The line c a of the plan, being at a right angle with the plane of delineation, will be represented by a line drawn to the point of sight, the vanishing point for all lines lying in that direction ; draw therefore the line c f, and where this intersects the perpendicular drawn from b y will be the position in the picture of the point A required, the line c A being the correct perspective length and direction in the representation, Fig. 1 6, of the line c A of the plan. Simple as the above diagram appears, it is important that it be most clearly understood. In making a perspective drawing consisting of a great variety of objects, the intricacy * The drawing a straight line from the point required to be found in the picture up to the plane of delineation, is called bringing the point up to the plane of delineation, and the position of it in the picture may be found by- bringing it forward in any direction ; but in this instance it must be brought forward perpendicularly, otherwise we could not find the position of the point a by means of the point of sight, that being the vanishing point only for lines at a right angle with the plane of delineation. Tin* will be fully explained in the ensuing chapter. 96 PERSPECTIVE FOR STUDENTS. of lines may at the outset perplex the student, which will pass away with practice ; but with a thorough comprehension of the principle on which the foregoing diagrams (Figs. 16) are drawn, he can never be at a loss to find the position of any given point in a picture, whether situated on the ground plane or above it, — as we shall presently show. By this mode any plane figure, however complicated, may be repre- sented in perspective by actual measurement of the original objects: for instance, suppose A, Fig. 16, to be the spot on which any object stands (a man, a tree, or a post, is im- material for our present purpose)*, distant perpendicularly from the plane of delineation four feet, the spectator being four feet in front of this plane, his eye situated three feet above the ground plane ; from these premises the position of this point may be ascertained with the greatest ease on a sheet of paper or other plane surface, and of any size required, in the following manner : — First, draw a horizontal line, on which mark a series of equal divisions, to serve as a scale to work from, similar to the diagram (Fig. 1?) here given,* Fig. 17. . 2 2 3 U 5 ____ *P which represents a scale of ten feet in length ; then draw a line c, equal in length to that of your picture (Fig. 16, Rep. 1), to represent the base line of your plane of delinea- tion ; and behind it, at the (perpendicular) distance of four feet,t mark the position of the spot on which the object * All geometrical drawings furnished to artists are worked on a scale of so much to a foot, yard, &c. according to the size required. Having the dimensions of the various parts to be represented, measurements are taken from the scale and applied to the drawing, by which the rela- tive proportion of the parts is preserved, however minute the repre- sentation. f The plan, Fig. 16, is worked to the scale here given, for the advantage of L h* student ; but in making his own drawing, it will be better to con- struct a much larger scale to work from. PERSPECTIVE FOR STUDENTS. 97 stands at A, to the right hand of the spectator, then on the picture, three feet of the scale above the ground line, draw the horizontal line, and from these find the position of the point as described, Fig. 16, Representation. Referring back to the diagrams, Figs. 16, at the risk of being accused of prolixity, we will once again go over the several parts; and we will first observe that the space be- tween the ground line 3 — 4 and the horizontal line e repre- sents a very great extent of flat surface, the whole extent of space between the situation of the plane of delineation to the greatest distance our vision extends ; that the point f is the point of sight, that point perpendicularly opposite the eye of the spectator, and the vanishing point for all lines at a right angle with the plane of delineation ; the perpendicular line over b shows that on some part of that line the point A will come, and the line c F determines at what point. We will now, by the same means employed for finding the position of the point a, find the position of another point on the same plane, b ; and that we may not interfere with the simplicity of Figs. 16, we will take a fresh diagram (Fig. 18), premising that the references marked A, B, c, D, e, and F, and a, c, are precisely similar to those in Fig. 16. Fig. 18, Plan. Let us place another point on the plane B, as at G, the position of which is to be found in the picture by the same process as we found the position of the point A, viz% a visual Perspective. F 98 PERSPECTIVE FOR STUDENTS. ray G d, must be drawn, and the point of intersection, d, carried to the ground line of the picture at d (Fig. 18, Representation), and a perpendicu- Fig. 18, Representation. fep y me dfawn ^ ;| . then bring the point G perpendicularly to the plane of delineation at e, carry this point to the ground line of the picture at 0, and from it draw a line to the point F ; the intersection, g, of this line with the perpendicular drawn from d will be the perspec- tive position of the point G of the Plan. If we suppose these two points a and g to be the extremities of a straight line, as shown by the dotted line a g in the Plan, then the dotted line A g in the Representation would be the perspective appearance of it. It must then be evident that as by this means we can ascertain the perspective direction and length of one straight line, the direction and length of any other may be found in the same manner, and consequently, any plane figure of straight lines may be drawn in perspective by means of the point of sight only as a vanishing point ; thus, if we place another point at H on the Plan, and draw the (dotted) lines h g, g a, and a h, we have the plan of a triangle ; and by rinding the position of h in the picture in the same manner as the points A and g were found (shown in the diagrams), by drawing the lines G A, A H, and g h, as is done by dotted lines in the Representation, it presents the appearance the triangle would assume viewed as described. Although the mode described in Figs. 16 and 18 for finding the perspective form of any plane figure would produce a correct representation were it ever so complicated, it would be found but a round-about method of proceeding where the figure contains a quantity of lines. The usual and most convenient manner of finding the perspective directions of lines that are at an angle with the plane of delineation is by means of their respective vanishing points ; and we will PERSPECTIVE FOR STUDENTS. 09 therefore proceed in the next chapter to point out the manner of finding the vanishing points for straight lines at whatever angle they may lie with the plane of delineation, and how- ever numerous the variety of their directions. CHAPTER IV. We have already more than once stated that all lines that in the original object are parallel, in their perspective repre- sentations incline towards each other and meet in the same point, somewhere on the horizontal line (see Part I. pp. 9, 10, Figs. 14, 15 ; pp. 11, 12, Plate 1, Fig. 2). It must be further understood, that in drawing a variety of objects, every change of angle a line makes in its inclination towards the plane of delineation requires a fresh vanishing point. Thus in the diagram (Fig. 1 9) the rectangular figures a, b, c, and d Fig. 19. represent the plans of four objects standing on the ground plane F, the situation of the plane of delineation being at E ; so situated, each figure would require two distinct vanishing points, the sides of each figure lying at different angles with the plane of delineation. The same would be the case in representing any polygon in perspective ; the sides of the F 2 100 PERSPECTIVE FOR STUDENTS. polygon being at different angles with the plane of deline- ation, would require distinct vanishing points. In order to find the vanishing points requisite for putting any object or combination of objects in perspective, it is indispensable to have the plan of them, the position of the plane of delineation (its base line drawn), and the position of the spectator. Whatever may be the direction of any Jne on the plan for which a vanishing point is required, it is found by ruling a line (parallel to the line on the plan) from the point marking the position of the spectator, and con- tinuing the same till it intersects the plane of delineation ; the point perpendicularly over this on the horizontal line will be the vanishing point not only for the line selected on the plan, but for every line parallel to it. Thus in Fig. 20, let A be the Fig. 20, Plan. d c position of a square, b the plane of delineation, and c the position of the spectator. The lines a b and c d being parallel lines in the geometrical plan, in the perspective representation must tend to the same point; to find this point, the edge of a parallel rule must be placed against either a h or c d, and brought down over c, from which PERSPECTIVE FOR STUDENTS. 101 point a line must be ruled till it intersect the line b,* as at e. The lines a c and b d are also parallel, but at a different angle with the plane of delineation to a b and c d, and will require a fresh vanishing point, which is found in the same manner ; that is to say, from the position of the spectator, c, a line pa- rallel to a c, or (what is the same thing) b must be drawn to the plane of delineation at /, and the point perpendicularly over this, on the horizontal line will be the vanishing point for the lines a c and b and for all lines in the plan parallel to them. Let us now carry these points from the plane of delineation to the ground line of the picture, as in the previous examples, and proceed to put the square figure in perspective, first drawing the horizontal line D in the Representation (the height of which depends on the height Fig. 20, Representation. E F V h e j k g h f of the spectators eye above the ground plane), and placing the vanishing points E and f on it respectively perpendicular * The plane of delineation being an imaginary plane, may be sup- posed to extend to any distance. The visual rays must come within that portion of it where the picture is supposed to be, and, as we have shown, the whole might be accomplished by using the point of sight ; in such case, no more than that space would be required : but it rarely happens when more than one vanishing point is required that they fall within the picture. Where objects stand in a direction nearly parallel with the plane of delineation, the vanishing points are at a great dis- tance. It is therefore necessary, in finding the positions of the vanish- ing points, to extend the line representing the plane of delineation some distance both to the right and to the left, and the same will be required with the horizontal line in order to mark the vanishing points on it. 102 PERSPECTIVE FOR STUDENTS. over the points e and /. On the plan, draw the visual rays a c and c c, carry their points of intersection, h, on the plane of delineation to the ground line of the picture, and draw perpendicular lines from each. As in the preceding examples, the point a will come somewhere on the perpendi- cular drawn from g, and the point c somewhere on that drawn from h. Now in order to find the position of a on the perpendicular drawn from gr, let us refer back to the square we put in perspective in a different position (Figs. 1 5, Plan and Representation), and we shall there find that in order to get the position of the point corresponding with a of our present figure, we first drew the visual ray b c, carried the point of intersection d to the ground line of the picture, and, as in the present case, drew a perpendicular line from it ; then in order to find the point of intersection on it, the point b was brought perpendicularly to the plane of deli- neation at /, / carried to the ground line of the picture, and a line ruled from it to the point of sight k, which gave the point of intersection b. In the present figure (20), the points a, 6, d are found in the same way as the corre- sponding points 6, A, c, j (Fig. 15) ; only as the vanishing point for the line a c in this case is not the point of sight, but the point F, instead of bringing a to the plane of delineation by a perpendicular line, it must be brought forward in the direction c a, as at j, and j carried to the ground line of the picture ; if a line be ruled from this to the vanishing point p, we have the perspective position of the point a on the perpendicular over g, and the perspective position of the point c on the perpendicular over h ; the line j 1 a of the Repre- sentation being the perspective length and direction of the line j a of the Plan, the line a c the perspective representa- tion of the line a c oi the Plan, and the portion c f of the line j a c F, the continuation of the line^ a c in the direction of the dotted line in the Plan, as far as it is possible for it to be seen. The positions of the points b and d might be found in the same way as that employed for finding the posi- PERSPECTIVE FOR STUDENTS. 103 tions of the points a and c, i. e. by drawing visual rays from b to c, and from d to c, carrying their points of intersection to the plane of delineation, and drawing perpendiculars from them, then bringing the point b to the plane of delineation in the direction d b, and carrying the point of contact to the ground line of the Representation. If from this point a line were drawn to the vanishing point f, its intersections with the perpendicular lines found by the visual rays b c and d c would fix the perspective positions of the points b and as the intersections of the line j f fixed the points a, c on the perpendiculars over g and h. This manner of proceeding, however, though perfectly accurate, is not the readiest way to determine the positions of these points ; it is quite suf- ficient to draw the visual ray b c, and carry the point of intersection, to the ground line of the representation, and draw a perpendicular from it, on some part of which the point b will come. The position of the point a is already ascertained, and the vanishing point for the line a b ; there- fore, if a line is drawn from a to the vanishing point E, the point of intersection with it and the perpendicular drawn from is the position of the point b. F being the vanishing point for the line b d (this line being parallel to a c), from b draw the line b F ; E being the vanishing point for the line c d (c d being parallel to a from c draw the line c e ; the point of intersection of the two lines b f and c e is the per- spective position of the point d of the Plan, and completes the perspective drawing of the square a of the Plan by means of the vanishing points. Having shown by the diagrams of Figs. 16 and 18 how a triangle (or any other rectilinear figure) may be drawn in perspective by finding the positions of the points at the extremities of the lines, using the visual rays and point of sight only as a vanishing point, we will now take a similar figure, and point out the manner of drawing a perspective representation of it by means of the respective vanishing joints for each line of the triangle, and comparing the former 104 PERSPECTIVE FOR STUDENTS. mode, that of Fig. 18, with the one we are about to describe, show that the result is the same. Fig. 21, Plan. c C Let A in the plan, Fig. 21, represent the triangle, b the plane of delineation, and c the position of the spectator. Find the respective vanishing points on the Representation (after draw- ing the horizontal line) for the lines a b, a c, and b c, the sides of the triangle a at D, e, and f ; * draw the visual rays a c and b c, and carry the points of intersection g^ h to the ground line of the picture, from each of which draw a per- pendicular line ; bring the point in the direction c 5, to the plane of delineation at /, carry j to the ground line of the picture, and to the vanishing point for the line b c (f) draw * This being a different figure to the last, and knowing from experience as a teacher how trifling a variation will sometimes confuse beginners in these matters, we repeat for their assistance the proceedings of the last figure ; from c, the position of the spectator, parallel to b c, draw the line c ft the point on the horizontal line perpendicularly over f will be the vanishing point for the line b c, or any lines that may be parallel to it. From c, parallel to a b, draw the line c d; the point d on the horizontal line perpendicularly over d, will be the vanishing point for the line a b and all lines parallel to it. From c, parallel to a c, draw the line c e,- the point e on the horizontal line perpendicularly over the point e will be the vanishing point for the line a c and all lines parallel to it. If a figure consist of twenty or more sides, each side in a different angle, their respective vanishing points may be found in the same manner. PERSPECTIVE FOR STUDENTS. 105 the line j f ; the intersection of this with the perpendicular from h is the perspective position of the point b. From the vanishing point D (the vanishing point for the line a b), through the point draw a line till it meet the perpendicular drawn from gr, this will give the position of the point ay* from a draw the line a e, the intersection of which with the line b f gives the perspective position of the point e, which com- pletes the figure of the triangle, a b c, in perspective, and by a mode much more simple than that described in Fig. 18. To prove, however, that the result would be the same whichever mode of proceeding were adopted, we have drawn the visual ray c c by a dotted line, and carried the point of intersection, to the ground line of the picture, from which we have also drawn a perpendicular (dotted) line. We have also by a perpendicular from c to the plane of delineation (c I) determined the position of the point of sight, which we have placed perpendicularly over I on the horizontal line at G ; the point c we have brought perpendicularly to the plane of delineation at m ; we have placed m on the ground line of the Representation, and from it drawn a line to the point of Fig. 21, Representation. F G E D \ / / 1 a ! ! i • i i * \ \ fglkmhej d sight, g. It will be seen that the intersection of this line with the perpendicular drawn from k is in the same point (c) as that where the lines a r> and b f intersect each other, * This is a much readier way of finding the position of a than if we had brought, as was done, with the point b, the point a of the Plan, in the direction b a, to the plane of delineation, carrying that point to the ground F 3 106 PERSPECTIVE FOR STUDENTS. proving that the same result may be arrived at by different means. After perusing the descriptions given, and examining the diagrams illustrating them, for rinding the positions of van- ishing points, a little attention ought to make the student comprehend why it is that the lines of original objects that are situated at a right angle with the plane of delineation have their vanishing point in the point of sight, and that those lines which in an original object are parallel to the plane of deline- ation have no vanishing point, but are drawn parallel to it, or rather to the ground line of the picture. This will be fully understood by comparing the plans of Figs. 20 and 21 with that of Fig. 15 ; for if we require to find the vanishing point for the sides b c j of the square d, Fig. 15, both of which are at a right angle with the plane of delineation, it is clear that a line drawn from c, the position of the spectator parallel to them, to the plane of delineation at a, must be perpendicu- lar to it, which is always the position of the point of sight. Again, according to this rule for finding the vanishing points of lines from a plan, if we endeavour to find one to which the sides b c and h j should be drawn, a line through the point c parallel to them must also be parallel to the plane of delineation, and consequently could never meet ; hence it is that all lines that in original objects are parallel to the plane of delineation, are drawn parallel in the perspective repre- sentations. This manner of representing objects is frequently called Parallel Perspective, and that where all the sides of an object are at an angle with the plane of delineation, Oblique Perspective. The object of this work not professing more than to make the student thoroughly comprehend the system on which he is to proceed in making perspective drawings, line of the picture, and from it ruling a line to the vanishing point d. The result is obviously the same, as it can make no difference whether the line a b d is commenced from one point or the other, the direction must be the same. PERSPECTIVE FOR STUDENTS. 107 the examples already given are sufficient, it is hoped, to enable him to draw any plane rectilinear figure in perspec- tive that may be put before him. No example has been given for drawing curves, but as we have in Part I. pp. 35, 36, already stated that in order to draw curves in perspec- tive, rectilinear figures must first be made, to get intersecting points through which the curves are to be drawn, the ex- amples already given are considered ample for the present. Nevertheless, before proceeding farther, the student, if so dis- posed, will find it to his advantage to take the plar of the circle (Part I. Prob. V. Plate VI.) with the right lines about it, and marking a point for the position of a spectator and a line for that of the plane of delineation, draw it in perspec- tive, as also Figs. 4 aud 6, Part I. Plate XIII. CHAPTER V. We have hitherto confined our examples entirely to the representations of plane figures, without taking into considera- tion at all the height or thickness of objects. We will now proceed to show how solid figures are to be drawn in perspec- tive upon the principles we have already laid down. In order to be able to give a correct representation of any solid figure in perspective, it is not only requisite that we should have the form of the base of the object on a plan with its relative posi- tion with the plane of delineation and position of the spectator, but we also require, either by drawing or description, the form and dimensions of its different parts. If the solid to be repre- sented be simply a cube, it is unnecessary to have more than the plan furnished, as, one face of a cube being given, the remaining five are known to be similar. It must be under- stood, that in drawing plans from which perspective draw- ings are to be executed, a mere ground plan will not be found adequate to the purpose, for as the base line only of 108 PERSPECTIVE FOR STUDENTS. the plane of delineation is used for finding the perspective positions of the different parts of a structure, projections, recesses, &c., though they may occur twenty or thirty feet above the base of a building, must be first drawn on the geometrical plan, their perspective positions found, and then carried up to the height required ; in fact, the plan of a building required for making a perspective drawing must consist not only of the ground plan, but of a series of hori- zontal sections to the very top, wherever any change of form occurs. This will be better understood as we proceed, and when we have occasion for such a plan, we will recur to the foregoing remarks. The cube being the most simple form of solid to put into perspective, we will select that as our first example. In Fig. 15, pp. 90, 91, 93, we have drawn in perspective the plan of a cube as seen in a certain position — in what is termed parallel perspective. In referring to this figure (in which it will be remembered that the sides b h and c j\ from their being at a right angle with the plane of delineation, have their vanish- ing point in the point of sight), the points b and c are said to be brought to the plane of delineation at / and which makes the distance between /and g exactly the same as that between b c and h j. To make this perfectly clear, let us suppose the dotted lines g c j and / b h to be grooves, on which the face of a cube perpendicularly over b c could be slid backwards and forwards ; if we were by means of these grooves to slide the square forward, we should positively bring the points b and c up to the plane of delineation. The pupil can therefore have no difficulty in understanding that in Fig. \b,fg on the ground line is the width of the square right up to the plane of delineation, and that the line b c in the Representation is the width the same line would appear at the distance of fboi the Plan from the plane of delineation. Now let us imagine the square d (Fig. 15) to be a base on which a cube stands, and that this cube could be slid forward on the grooves, up to the plane of delineation. We should then PERSPECTIVE FOR STUDENTS. 109 have the front face of a square absolutely on the plane of deli- neation ; we should have a perpendicular line over /the length of b c, one of equal length over and a line parallel to / g passing from the top of one to the top of the other ; in fact, the form of the square on the plane of delineation (see Fig. 22, Rep.). It is unnecessary in constructing this cube to go over Fig. 22, Plan. the ground a second time for rinding the position of the square D on the picture, as in Fig. 15, the plan of which we have given again in Fig. 22. The square in this plan is placed distant from the plane of delineation exactly its own width, and for the advantage of showing the lines more dis- Fig. 22, Representation 1. i g tinctly, the position of the spectator a little to the left. Those points on the plane of delineation only are introduced that 110 PERSPECTIVE FOR STUDENTS. are requisite for drawing the square in perspective, as de- scribed for Fig. 15, Representation 2 ; and in the diagram of the Representation, Fig. 22, all lines are erased but those necessary for our present purpose. In case the student may have forgotten any portion of the directions for drawing Fig. 15, Representation 2, Jie can refer back to p. 93 to refresh his memory. We have above stated, that in order to find the points for constructing a cube in perspective standing over the square b c j A, we must suppose the face of it opposite to the spectator, to be brought forward to the plane of delineation, and according to that description, we must construct a square on the line / (7, as / g k I, which is really the geometrical elevation of the cube of its full size. It is very evident that the perspective position of the point k must come some- where on a perpendicular line over the point 6, and the perspective position of the point I somewhere on a perpen- dicular line drawn from c ; draw then from each of these points, b and c, an indefinite perpendicular line, and from each of the points k and I draw a line to the vanishing point (the point of sight) k ; where the line k K intersects the perpendicular drawn from b at m, it gives the perspective position of the point k ; where the line I K intersects the perpendicular drawn from c at w, it gives the perspective position of the point I ; by joining the points m and w, we have in the figure b c n m the appearance of the figure f g Ik at the distance of / b from the plane of delineation shown in the Plan, and the plane b c m n* being parallel to * The student must here understand, that as we speak of the lines in the plane figure of the square in the Plan being parallel to or at an angle with another line, so do we speak of the planes in a solid figure ; thus the square surface perpendicularly over the line b c we call a plane parallel to the plane of delineation, as we also call the perpendicular sur- face over the line h j, the surfaces of the back and front of a cube neces- sarily being parallel. In speaking of the sides of the cube perpendicularly over the lines b h and c j, we say that the planes of the sides are at right angles with the plane of delineation. The top and bottom of the cube are PERSPECTIVE FOR STUDENTS. Ill the plane of delineation, does not change its form, but only decreases in magnitude according to its distance. The angles of the cube standing over the points h and j of the Plan, must now be drawn perpendicularly from the points h and j of the Representation, that from h up to the line k k at o, and that from j up to the line I K at p ; by joining the points and jp, h j p o will be the representation of the square plane at the back of the cube ; this also being in a plane parallel with the two former, still preserves its geometrical form, though smaller from its increased distance. Thus, b c n m being the position and form of the front of the cube, and h j- p o of the back, m n p o must be the appearance of the top, and b m o h of the side that is visible, it being unne- cessary to point out that the sides of the top and the side of the bottom that is seen, must have been drawn in determining the positions of the points A, o, and p. If another cube stood over the square in the Plan f g cb, the square f g Ik would represent the front, b c n m the back,* and consequently 1 n m k the top, and / k m b the side visible to the spectator. In this figure, as in Fig. 15, Representation 2, in order that the principle on which the different planes of the cube are drawn should be well understood, more lines are intro- duced than are absolutely required to represent the figure it assumes ; a more simple manner of drawing the Representa- tion would be as shown in Fig. 22, Representation 2. Having drawn (as described, Fig. 15) the square b c j h m per- spective, draw from each of the points, 6, £, and an indefinite perpendicular line ; from the point g, set up the perpendicular height of the cube at Z, and from / draw the also in planes at right angles with the plane of delineation, but they are in horizontal planes, and the sides in perpendicular planes. It is as easy, after a little practice, to comprehend the terra " plane," as the word " surface." * In order to find the positions of certain points, it is frequently necessary to draw parts that cannot by possibility be seen, and in order to make this figure perfectly intelligible, several lines are drawn as if the cube were transparent. 112 PERSPECTIVE FOR STUDENTS. line I K ; where I K intersects the perpendicular from c, it gives the point n of the preceding figure. The top of the cube being parallel with the bottom, n m must be parallel Fig. 22, Representation 2. K to c b ; draw then from n a line parallel to c 6, and where this intersects the perpendicular from 6, it gives the point m ; from m draw the line m K ; the intersection of this with the perpendicular from h gives the point o ; o p being parallel to m n, draw from o, parallel to m n, a line to meet the line I k, which gives the point p : the intersection of these two lines obviates the necessity for drawing a perpendicular from j. Suppose another cube to stand upon the square e, and it is required to put this cube also in perspective behind the cube D. To do this, we must draw the visual rays 1 c and 3 c, and carry the points of intersection 5 and 6 to the ground line of the Representation, and from each point draw a perpendicular line between / K and m K ; from the points of intersection on / k draw horizontal lines to meet the line g k ; from the points of contact on g K draw perpendicular lines to meet the line I K ; from the points of contact on I k draw horizontal lines to m K ; the points of contact with the line m K will be the same as with those from the perpen- diculars drawn from the points 5 and 6, and will complete the perspective drawing of a cube standing over the square E of the Plan. PERSPECTIVE FOR STUDENTS. 113 Let us place a third square (p) on the plan, over which we will suppose another cube to stand, and we shall perceive with how much facility this third cube may be drawn in perspective. Bring the points 7 and 8 to the plane of delineation at 9 and 10 (in the same way as the points b c of the square D were brought to /, g) ; bring these points to the ground line, and from each of them draw a line to the vanishing point K. The square F being (as is seen in the Plan) at the same distance from the plane of delineation as the square e, all the points for drawing the square F and the cube standing on it may be found from the cube e already drawn, as follows : continue the horizontal lines 2 — 1 and 4 — 3 till they intersect the lines 10 K and 9 k; from the points of intersection 7 and 8, 11 and 12, draw up indefinite perpendicular lines ; continue the horizontal line of the top of the front face of the cube e to intersect the perpendiculars from 7 and 8 at the points 13 and 14, and from each of these draw a line to the vanishing point K. If a line be now ruled from the points where the lines 13 k and 14 k intersect the perpendiculars drawn from 11 and 12, it will complete the perspective drawing of the cube standing over the square f of the Plan, and show that having by means of the visual rays fixed the positions of certain points in one object, the positions of the points required for drawing another object may be found from the first without the necessity of additional visual rays, and the result will be the same with less labour. To illustrate this, we have intro- duced the visual rays 8 c and 7 c, and placed the points of intersection r on the ground line ; it will be seen by the perpendicular (dotted) lines drawn from these points, that they pass directly through the points 7 and 8, found by a different mode. The principle on which a solid is drawn in perspective, where all the planes are at an angle with the plane of delineation, is as simple as the one just given, Fig. 22, where some of the planes are parallel to it. In the example 114 PERSPECTIVE FOR STUDENTS. given, p. 100, Fig. 20, we have put in perspective a square having all its sides at an angle with the plane of delinea- tion. Let us refer to these diagrams, Figs. 20, supposing a cube to stand over the square A, and proceed to draw a Fig. 23, Plan. perspective representation of it, according to the Plan.* In this representation, the square a is put in perspective in the manner described for the Representation, Fig. 20, and the Fig. 23, Representation. E P r d> c ? > % a f q h g jh 8 e * The same plan we have given, Fig. 20, would fully answer the pur- pose for constructing a cube on the square a, but a new one is considered requisite, in order to introduce some additional lines, which would have caused considerable confusion if put into the former one; the principle for drawing it is the same, although the figure is reversed. PERSPECTIVE FOR STUDENTS. 115 point a is brought to the plane of delineation at j\ as the point c of Fig. 22 was brought to the plane of delineation at only that as the side c j is at a right angle with the plane of delineation, the point c is brought (following the direction of j c) perpendicularly to it ; whereas the line a c of Fig. 23, not being at a right angle with the plane of delineation, the point a is brought to it in the direction of c a. From this point j, set up the perpendicular height oi the cube (the length of any side of the square A of the Plan) at I ; this point will determine the height of the four angles of the, perspective square over the points a, 6, c, d ; we have already got the perpendiculars from a, 6, and £, in the lines drawn from g, and A, and may therefore proceed at once to determine the height of them. From I draw a line to the vanishing point F, which will determine the height of the perpendicular lines over a and c at m and n, as the line I K (Fig. 22, Representation 2) determined the positions of the points n and p. The point m, in Fig. 22, Representation 2, was found by drawing a line parallel to the ground line from a to intersect the line drawn up from 6, on account of the plane c n m b being parallel to the plane of delineation ; but the plane standing over the line a b, Fig. 23, being at an angle with the plane of delineation, all the horizontal lines on that plane must be drawn to the same vanishing point ; therefore from the point m, a line must be drawn to the vanishing point E, the intersection of which w r ith the perpendicular from 6, determines the height of it at o : if a line be now drawn from o to the vanishing point f, and from n to the vanishing point E, the point of intersection p of the two lines will be found perpendicularly over and completes the perspective drawing of a cube standing in the position de- scribed in the Plan, Fig. 23. In order to determine the heights of the different angles of the cube a m, c n, d p, and b o, it is immaterial whether the point a is brought to the plane of delineation in the direction c a to j, or whether it is brought forward in the 116 PERSPECTIVE FOR STUDENTS. direction b a ; in fact, either of the three points a, 6, or c, would answer equally well to find the heights of these per- pendicular lines ; for if the point c were brought forward to the plane of delineation in the direction of the line d as at q (in the Plan), and this point carried to the ground line of the Representation, a perpendicular drawn from it the geometrical height of the cube, will be found to produce the same result as that produced by the point /, as is shown in the Representation. The point q is placed on the ground line, and the geometrical height of the cube set over it at r ; from r a line is drawn to the vanishing point E, and it will be seen that the point of intersection with the perpen- dicular from £, is in the same point with that drawn from I to the vanishing point F ; and the intersection giving the point p must necessarily be the same. Again, if the point b was brought forward to the plane of delineation in the direction d 6, as at s (Plan), s carried to the ground line, and the geometrical height of the cube set over it at £, and this point chosen for determining the height of the per- pendicular angles, the same result would ensue as in the two preceding cases ; the line t f intersecting the perpendicular from b in the same point as the line m e. If the perspective height of the cube is to be determined from the line q r on c it determines by the same line the height of dp ; the point m would be found by ruling a line from the vanishing point f through n to intersect the per- pendicular from a ; the intersection will be found in the same point as found by the line I F ; the point o, in this case, would be found on the perpendicular line from 6, either by the intersection of a line drawn from the point m to the vanishing point E, or of a line drawn from the vanishing point F, passing through the point p. It has then been clearly shown that any point may be selected, and that the perspective height of the cube being found at any one angle, the height of the remaining three may be determined from it. The student, if he has paid attention to the directions PERSPECTIVE FOR STUDENTS. 117 given tor drawing all the preceding figures, ought now to be able to draw in perspective with tolerable facility a more com- plicated one than any we have yet used for our illustrations, and that by simple description, By a mere servile copying, in his progress through the work, the diagrams we have introduced, he may be liable to forget some of the earlier ones in his anxiety to get forward, and he is strorgly recom- mended, as he proceeds, not only to draw with care and more than once each separate figure as it occurs, but to vary the positions of the objects or the spectator in his plans, and then put them in perspective. To draw an octagonal tower from a plan in perspective, is not more difficult than to represent the cubes in Figs. 22 and 23, it only requires a greater number of lines ; but by a careful attention to the rules we have already given, a tower of any number of sides may be drawn without the necessity for any extra directions, as it ought to be quite superfluous to inform the student, that if the hori- zontal lines that in the perspective representation tend to any vanishing point are situated above the spectator's eye, they incline downwards instead of upwards. In order, therefore, that the student may satisfy himself that he has fully com- prehended the foregoing rules, we will furnish him with the plan of an octagon tower, with the relative situations of the spectator and tlie plane of delineation, of which he must draw the perspective representation from description. We have, therefore, in the diagram (Fig. 24) given the plan of the tower, a, the position of the spectator at c, his eye situated five feet above the ground plane, and the plane of delineation at B, marking each angle of the tower at 1, 2, 3, 4, 5, 6, 7, 8. According to the position in which the spec- tator is placed in looking at an octagon tower, he may see either three or four of its sides ;* in the position in which it is * It is possible to place the spectator opposite either angle of the octagon, so that only two sides would be visible ; indeed, if he were close to such a tower, perpendicularly opposite either of the sides, that side only would be seen. But we shall be able to point out in our remarks on the 118 PERSPECTIVE FOR STUDENTS. here placed, four of the sides are visible, 8 — 1, 1 — 2, 2 — 3, and 3 — 4. The width these sides would appear in the picture is deter- mined by the visual rays drawn from the points 8, 1, 2, 3, 4, precisely similar to the manner of finding the width of the sides of the cube, Figs. 22 and 23 ; the points of intersection, a, 6, c, 0, on the plane of delinea- tion, must be carried to the ground line of the picture, from each of which a long perpendi- cular line must be drawn (the top of the tower be- ing considerably above the eye of the spectator). In the position of this figure relative to the plane of delineation, we see that the lines 1 — 2 and 6 — 5 are parallel to it, and consequently have no vanishing point ; that the lines 3 — 4 and 8 — 7 are at right angles with it, and will , consequently have their vanishing point in the point of sight ; that the pa- rallel lines 1 — 8 and 4 — 5, being at an angle, not a right angle, with the plane of delineation, require a distinct vanish- ing point, as will also, for the same reason, the parallel lines positions to be chosen for making perspective drawings, that those posi- tions where only one or two sides are seen are such as are inadmissible for making perspective drawings. PERSPECTIVE FOR STUDENTS. 119 2 — 3 and 7 — 6. The position of these vanishing points then must; be found on the plane of delineation, as described in Figs. 20 and 21, carried to the ground line, and perpendicu- larly over them set on the horizontal line. Having set these points on the horizontal line, that is, the point of sight, which should be marked D,* the vanishing point for lines parallel to the sides 1 — 8 and 4 — 5, which mark e, and the vanishing point for the sides 2 — 3 and 7 — 6, which mark f, proceed to draw the figure in perspective. It is immaterial, in determining the positions in the picture of the points 1 and 2, which of them is brought to the plane of delineation, as the position of one being ascertained, the other may be got from it (see the points £, and Fig. 23). Let us choose the point 1, and we shall find that it is imma- terial also whether this point be brought perpendicularly to the plane of delineation at /, or in the direction of the side 8 — 1, at g. If the former, f would be carried to the ground line, and a line ruled to the point of sight d, the intersection of which with the perpendicular drawn from would be the perspective position of the point 1 ; if the latter, g would be carried to the ground line, and a line ruled from it to the vanishing point E, which would intersect the perpendicular from b in the same point as the line / d (Fig. 21). The position of the point 1 being ascertained, the remaining corners may be found from it ; as, from 1 draw a line parallel to the ground line, where this intersects the perpendicular from c is the point 2 ; from this point draw a line to the vanishing point f, the point of intersection with the perpen- dicular from d is the position of the point 3 ; from 3 draw a line to the vanishing point d, the point of intersection with the perpendicular from e is the position of the point 4. If g be the point chosen from which the position of the point 1 is determined by g e, the same line will give the point 8 * The student must be careful to mark the references as they are de- scribed, as he proceeds ; he will by this means get on without difficulty ; by neglecting to do so, he will get sadly perplexed. 120 PERSPECTIVE FOR STUDENTS. at its intersection with the perpendicular from a; if the point 1 be determined by the line / D, then a line mus be drawn from the point 1 to the vanishing point E to deter- mine the point 8. These four lines, 8 — 1, 1 — 2, 2 — 3, and 3 — 4 of the base of the octagon tower, are all that can be seen from the station c, and we have now to determine the heights of the perpendicular angles over these points 8, 1, 2, 3, 4. The perpendicular lines from these points are already drawn, and the height of one being determined, the heights of the remainder may be ascertained from it. Supposing the height of the tower to be five times the length of from 1 to 2, this height must be set up on a perpendicular line from the point g (on the ground line), and marked 7i, from which point a line drawn to the vanishing point E will deter- mine the height of the angles of the tower over 1 at j and 8 at k; the heights of the three remaining angles standing over 2, 3, and 4, may be determined in the same way that the points 2, 3, and 4 were found ; that is, from^ draw a line, parallel to the ground line, to the perpendicular from c; from the point of intersection draw a line to the vanishing point f till it meets the perpendicular from and from this point of intersection, a line to the point of sight d to meet the per- pendicular from 0, which will complete the drawing of an octagon tower, viewed from the position shown in the plan, Fig. 24.* * In giving the description for putting this figure in perspective, we stopped at finding the positions of the points 8 and 4, four sides of the octagon only being seen from the position at c. It may be as well to point out how the whole plan of the octagon might be completed from the points already found, without drawing any additional visual rays. It will be seen that the lines joining the points 2 and 3 with 7 and 6, are parallel with the lines 1 — 8 and 4 — 5, and consequently, to represent them in perspective they must be drawn to the same vanishing point e : therefore from 8 draw a line to the point of sight d, and from 2 draw a line to the vanishing point e ; the intersection of these lines gives the point 7 ; from 7 draw a line to the vanishing point f, and from 3 to the vanishing point e ; the intersection of the lines gives the point 6 ; PERSPECTIVE FOR STUDENTS. 121 Fig. 25. An experiment practically proving the accuracy of a series of diagrams, not only tends to fix certain principles in the mind of the student, but frequently, if the principles are but imperfectly comprehended, is an inducement to him to retread his ground, in order to render himself capable to become the exhibitor of the same in his turn ; and moreover, the satisfaction derived from witnessing the perfection of an experiment gives great encouragement for perseverance in the continuation of his studies. To this end we propose describing a simple but most satisfactory experiment, that will afford a convincing proof of the correctness of the principles on which the preceding figures have been drawn. In the annexed diagram, Fig. 25 (the whole of which is drawn to a scale from the ob- jects described), the parallelogram B A B c D represents the top of a common table, upon which over the square E stands a cube ; * on the line c D (which represents the edge of the table), take any point as the position of the spectator, which we have here fixed at f, and across the table parallel to the edge c I), draw a line G h, to re- present the base of the plane of delineation, over which the plane of delineation is supposed to d~ stand; then from the corners of the object on the table, draw the visual rays ; find the from 4 draw a line to the vanishing point e, and from 6 a line parallel to the ground line to meet it ; the point of intersection will give the point 5, and complete the figure of the octagon in perspective. The same result might be arrived at in various ways, but the principle would be the same. * We are obliged to specify some particular figure, but a work-box, desk, book, or other object, no matter what, may be chosen* Perspective, q 122 PERSPECTIVE FOR STUDENTS. Fig. 26. c b a f position of the point of sight by a perpendicular from p, and bring one of the angies of the square on which the cube stands perpendicularly to the plane of delineation, as described in Figs. 15 and 16. Construct a parallelogram 1, 2, 3, 4, to contain the representation ; carry all those points to the ground line, Fig. 26, and then draw the cube in per- spective as described in Fig. 22. The representation, to answer the purpose of our experiment, must be drawn on a piece of stiff paste- board ; the height of the horizontal line being placed above the ground line, the same height the eye is situated above the edge of the table c d, and should be sufficiently elevated to enable the top of the object to be distinctly seen. A strip of card must now be cut similar to K, Fig. 26, a straight line 5 6 drawn across it, and from this a perpendicular line must be drawn the length of the space from the ground line to the horizontal line, to at which point drill a small hole with a pin. Place this strip of card upright on the edge of the table c D, the point 5 at the point 7, and the point 6 at 8, which will bring the point g exactly opposite the point of sight. Let the form of the cube (the whole of the tinted figure) in Fig. 26, be carefully cut out, and the piece of pasteboard on which it was drawn set perpendicularly on the table in the place where the plane of delineation is supposed to be situated ; the point 3 standing on g, and the point 4 on n, the points/, a, 6, c, d must necessarily come over their cor- responding points on g h, and the hole g in the card per- pendicularly opposite the point of sight J. If in this position of the different parts, the student place his eye close to the hole g in the strip of card k, he will find the cube, PERSPECTIVE FOR STUDENTS. 123 standing over the square e, to fit exactly to the hole cut out of the pasteboard. In order to be quite successful in this experiment, a perfect adjustment of all the parts is indis- pensable ; the drawing must be made with great accuracy, and the greatest care must be taken that the piece of paste- board containing the figure of the cube, and the slip of card through which the hole is pierced, stand perfectly perpendi- cular to the plane of the top of the table. This experiment may be repeated with advantage in a variety of ways, all of which variations will illustrate some portion of the text in the preceding chapters. It will bo found, that the slightest change in the position of any of the parts will destroy the effect : the position of the eye must neither be moved to the right nor left, neither higher nor lower ; if the line G h were drawn closer to c d, the hole would be too large for the cube to appear to fit it ; if it were dr^wn farther back, the hole would appear too small ; any change in the position of the cube itself would alike destroy the effect. If only one face of the cube were to be drawn, the figure would be similar to D, the representation of A, Fig. 11 ; in such a figure, whether the square stood parallel to or at an angle with the plane of delineation, if pieces of twine were attached to the four corners of .the real square, the four strings first passed through the hole cut in the pasteboard standing over g h, then through the hole g in the strip of cardboard, and the strings pulled tight so as to form straight lines from the original square to the point they would be found to touch the four corners of the hole representing the form of the square in perspective ; thus referring to Fig. 11, and supposing a to be the front of the cube, D the hole cut in the pasteboard, and the point E the hole in the sirip of cardboard, the strings from the corners of the original square drawn tight to the point w^ould touch thr* four corners of the hole cut in the board, as the lines drawn from the corners of the square A to E, touch the corners a y 6, d y of the souare D. a 2 124 PERSPECTIVE FOR STUDENTS. For teachers at schools, or for those who receive pupils in classes, a small apparatus for this experiment would be attended with a very trifling expense, and would prove as advantageous to the teacher as to the pupil : to illustrate by experiment being easier to the master than by description, and much less difficult of comprehension to the scholar. Any figure may be selected for this experiment, and the representations of circular figures, to those not conversant with perspective drawings, cause considerable astonishment. After an attentive examination of the rules contained in the preceding chapters, the student ought to experience no difficulty in finding the situation on the horizontal line of all vanishing points that are requisite for drawing in perspective any plane figure, however complicated ; nor do we think he ought to be at fault in constructing a solid figure upon it ; it is frequently, however, necessary to have on the same plan a variety of figures, drawn one within the other, representing projecting and receding parts situated over the plan. To represent these in perspective with accuracy, requires great attention and considerable nicety ; and as we have given no figure of this kind either in this or the first part of our work, we will introduce a plan and perspective view of one of the buttresses of Magdalene Bridge, Oxford, which affords an excellent example for illustration. Before, however, pro- ceeding to any more complicated representation, we propose to make a few general observations, and compare the pro- cesses described for drawing perspective in the First and Second Parts. In the various diagrams we have already given, it must be quite evident that the same result in finding the perspec- tive positions of points in a picture is to be attained in a variety of ways ; and though, in the first instance, in order to determine the position of some leading point or points from which others may subsequently be drawn, it is requisite that the relative positions of the plane of delineation, &c, must be fixed, so that the general outline of the subject shall be PERSPECTIVE FOR STUDENTS. Fig. 27. Station, ® 126 PERSPECTIVE FOR STUDENTS. arranged by the visual rays and vanishing points, much of the detail may be accomplished by more simple means. This is clearly shown in the manner of drawing the perspective cube f, in Fig. 22, Representation 2, the whole of which may be drawn without the necessity for introducing any visual ray at all. The same may be observed by referring to the Representation, Fig. 21, where the point c of the tri- angle is formed by the intersections of the lines a D and b F, without the necessity of a visual ray, as is also the point d in the Representation, Fig. 20. Those modes for making perspective drawings that are attended with the fewest number of lines are always to be preferred ; and it would surprise many who are not accus- tomed to execute drawings in perspective, to witness the rapid and very simple manner in which intricate drawings are made by those who make it their business. In our endeavours to explain with sufficient clearness the manner of finding the perspective positions of certain points by means of drawing the visual rays through the plane of delineation, we have in every instance made the plan quite distinct from the repre- sentation, which is really the fact, as it must never be lost sight of that the picture you are making is to represent the original objects as they would appear if traced on a sheet of glass (-the plane of delineation) placed between the spectator and the objects to be drawn. The manner most commonly in use, however, is to make the ground line of the picture and the ground line of the plane of delineation the same line ; to place the position of the spectator above this line according to his distance from the plane of delineation and the plan of the original objects below it, the points of inter- section of the visual rays on the ground line of the plane of delineation thus come at once on the ground line of the pic- ture;* those points required to be brought forward to the * The student must understand, that in the diagrams given in this Part of the work, as well as in the figures of the Problems in Part I. for the purpose of instruction, lines of all kinds, whether to vanishing points, to PERSPECTIVE FOR STUDENTS. 127 plane of delineation are brought at the same time to the ground line of the picture. This process is a much readier mode than making the base of the plane of delineation ana the ground line of the picture two separate lines, as we will show in our next figure. The original object of the First Part of this treatise on per- spective was to furnish information just sufficient to enable the amateur to make sketches from nature without violently outraging perspective. The forms chosen and the directions given for drawing them were as simple as the subject would admit, and the Author trusts that it is impossible for any intelligent person to go steadily through the pages without comprehending the matter. Although the present Part goes much farther into the art of perspective than the First, and the mode pointed out for representing the perspective forms of objects is different, yet there is nothing in the First Part of the work to unlearn; an attentive perusal of the two parts, with careful drawings made on a larger scale from the illus- trations contained in both, we may venture to say, would enable the student to draw in perspective any geometrical figure set before him. It may appear to some that in giving rules for drawing a number of figures in perspective in the First Part, and leaving the explanation of the principles on which perspective drawing is founded for the Second, is, to use a homely adage, putting the cart before the horse ; but perspective is generally allowed to be an extremely difficult subject to write on, as it is necessary before we can enter into the principles on which perspective drawing is founded, distance points, or the visual rays that are requisite fo»* rinding points of intersection,— in all cases the whole length of the line is drawn from point to point ; but in the execution of a perspective drawing, where all lines for finding the form required are erased, this is not required. All that is necessary is to place the rule from point to point, and mark delicately, but distinctly, only the point of intersection required. By this proceeding a vast confusion of lines is obviated, and the progress of the drawing rendered more simple. 128 PERSPECTIVE FOR STUDENTS. first to understand what perspective really is. To those who are ignorant of drawing, the geometrical elevation of a building appears more correct than a perspective representa- tion, yet to those who understand the principles of drawing it must be quite evident that a geometrical elevation, how- ever useful it may be, cannot be a correct representation of what we see, let the position of the spectator be where it may ; as a simple geometrical drawing does not represent the thicknesses either of projections or recesses, though they may be ascertained generally by the depth of the shadows. The frontage of a rectangular building may be so situated with reference to the position of the spectator, as to present a rec- tangular figure, but all recesses or projections on the face of it must be drawn according to the rules of perspective if the representation be really as it appears, which is not done in a geometrical elevation. Hence we have preferred the system of showing practically by the most familiar examples, in the First Part, in the various figures from 7 to 15, that objects vary considerably in their form according to their change of position with reference to the spectator ; that parallel lines viewed in certain directions appear to meet in a point called the vanishing point ; how the position of these vanishing points may be found on the horizontal line with sufficient accuracy for ordinary sketches, with directions for determin- ing the height of this line ; and then proceeding from these premises to put a variety of figures in perspective ; showing in the First Part what is meant by perspective drawing, and leaving it to the Second to point out the principles on which it is grounded. The First Part, in fact, being but an intro- duction to the Second, the proper understanding of which is greatly facilitated by an acquaintance with the First, some of the diagrams of the Second being difficult to comprehend without this knowledge. In referring back to the first problem, Part I. p. 15, if we were to proceed to draw a similar figure on the principles we have described in the Second Part, which would be on the PERSPECTIVE FOR STUDENTS. 129 same plan as the Representation, Fig. 23, we should find that after determining the positions of the lines a, e, f by means of visual rays, and finding the positions of the vanish- ing points G and H, as shown in the diagrams Figs. 20 and 21, by which the inclinations of the lines D, c, H, and J are drawn, all the remaining parts may be as accurately deli- neated by the system described for drawing this problem, pp. 15 — 21, Part I., as if done by the rules given for draw- ing the diagrams Figs. 22 and 23, as it is immaterial as affects the accuracy of the drawing, whether the positions of the points necessary for finding the width of the windows, which were determined by means of a distance point, or the point necessary for drawing the point of the gable, which was determined by the use of diagonal lines, be found by the means used in drawing Prob. I., or whether the positions of all the points are found by means of the visual rays; whichever mode is employed the result will be the same. The point of distance is most valuable in perspective draw- ing, and a variety of ways are shown by different writers on perspective by which the position of this point may be deter- mined. In the directions given for making perspective representations of objects embraced in the diagrams from Fig. 15 to Fig. 24, it must be very evident that the whole of a perspective drawing may be executed without the necessity for employing a distance point at all, the visual rays answer- ing the same purpose ; but it is frequently the case that the introduction of a distance point saves considerable labour, and the directions given for fixing its position in Prob. I. and II. Part I., and elsewhere, are sufficient for any pur- pose, as they will produce intersecting points on any line with as much accuracy as is to be obtained by visual rays. If a drawing of the plan of the house, the original object of the representation, Prob. I. Part I., were given to the student, with the position of the spectator and situation of the plane of delineation, it is barely possible he could have any difficulty in putting in perspective the parallelograms of G 3 130 PERSPECTIVE FOR STUDENTS. the two sides of the house, formed by the lines a, d, f, k and a, c, E, J ; the heights of all the different parts being the same as described for drawing the first problem, Part L In the cut (Fig. 27) we have here introduced, we have placed the plan of the building below the ground line, so as to bring the intersections of the visual rays direct to it ; this will prove a great saving of labour ; but it is necessary to point out, that in all cases where this is done, the plan must be drawn the reverse way to that where the base line of the plane of delineation and the ground line of the picture are distinct lines, which has been the case in all our previous examples. This will be understood, by turning the figure 27, upside down ; in looking at it in this position, taking the ground line of the representation as the base of the plane of delineation, if the points of intersection on it were carried to another line as the ground line of the picture (similar to the diagrams, Figs. 22, 23), the gable end would be to the right hand instead of to the left, the way we absolutely see it. It is not our province to enter into any theories ; all that is required is to make the student understand as a practical fact, that where the plan is placed underneath the picture, so that the base line of it (the ground line) is used at the same time as the base of the plane of delineation, the plan must be drawn reversed ; by making the ground line serve both purposes, we gain a saving of labour, which is always an object. The annexed diagram shows that the result will be the same, whether we use a distinct line for the base of the plane of delineation, carrying the intersecting points to the ground line of the picture, drawing the plan as it stands before us, or whether we make one line serve the purpose of both, by drawing the plan reversed. Let A represent a plan similar to that in Fig. 27, only drawn as it stands before us, B representing the plane of delineation, from which the points are to be carried to the ground line of the picture, c the position of the spectator. The plan a is a reversed, and the point c is in the same relative position to a as c to A ; the PERSPECTIVE FOR STUDENTS. 131 Fig. 28, line B serving for the plan a and station point c, both as ground line of the picture and base of the plane of delineation ; the visual rays b c and d c, it will be seen, intersect the line B in the same points as the visual rays b c and d c. In comparing figure 27 with Plate II. of the First Part, it will be seen that the lines K and J in the plan, are the lines by which the positions of the vanishing points H and J are deter- mined ; the angle a of the house touch- ing the plane of delineation, is of course drawn perpendicularly up from the point 2 ; the perpendiculars E and F are determined by the visual rays drawn from a and b to the station point of the spectator © ; the lines c, J, D, and k, are drawn as in Fig. 23, Representation.* The points by which the perspective width of the windows was determined in drawing the house in Prob. I., was by means of a distance point, full directions for the manner of determining the position of which, were given in the directions for drawing that problem ; and we here propose to show that the result of finding them by this means is precisely the same as if the visual rays had been used. The distance from 1 to 9 in this diagram (Fig. 27), will be found to be really the geometrical length of the perspective line d, by comparing it with the line K of the plan, and the divisions 10, 11, 12, 13, correspond on the two lines R and K. From each of the points 10, 11, 12, 13, on K of the plan, draw a visual ray to the station of the spectator, intersecting the ground line (also the plane of delineation) at c, d, e 9 /t From the point 9 through the * As regards the height of the line a and the height of the windows, the manner of determining them was fully explained at p. 20, Part I. f In this figure, to avoid confusion of lines, the visual rays are not drawn to the station point through the ground line, but only up to it 9 132 PERSPECTIVE FOR STUDENTS. corner of the house, 5, draw a line to the horizontal line, to determine the point of distance, s;* then from each of the points 10, 11, 12, 13, on r, draw a line to the distance point s, to determine the perspective positions of these points. If we now from each of the points on the ground line, c, d, 0,/, draw a perpendicular line up to d, they will be found to intersect that line in the same points, as the lines drawn from the points 10, 11, 12, 13, on r, to the point of distance s, proving that the positions of these points are determined with as much accuracy by means of a point of distance, as by drawing the visual rays. In Prob. I. Part I., the perpendicular line dividing the parallelogram A, c, e, j into its perspective halves, was found by means of the intersection of the diagonal lines l and m at the point 7 ; we shall find this mode for drawing the perpendicular line N at its perspective distance from a and e, equally correct as employing either a visual ray or a point of distance. The point g on the plan is exactly midway between 2 and a on the line J ; if from this point a visual ray is drawn to the ground line at a perpendicular line drawn from it will pass directly through the point 7 found by the intersection of the diagonals l and m. Again, from the point 1 on a, a horizontal line 1 j is drawn to represent the geometrical length of the line c (equal to j of the plan) ; if from j through the point 3 a line is ruled to the horizontal line, it will give a point of distance T, by which the width of any details on the gable end of the house may be determined on the line c ; thus, if from the point the half of the geometrical representation of c, a line is drawn to the point of distance T, the intersection of it with the line c determines the perspective centre, and is in the same point with the were it not a figure for instruction, even this would be unnecessary, as simply marking the points of contact at c, d, e, and f, would be sufficient. * All the references in this figure that occur in Proh. I. Part I., are lettered and figured the same. PERSPECTIVE FOR STUDENTS, 133 intersection produced by the perpendicular line from 7 and L Hence it must be clear, that to determine the perspective distance of any perpendicular line between a e or A F, it is immaterial, so far as correctness is to be obtained, whether these distances are determined by a distance point, by visual rays, or by means of diagonal lines.* It is difficult to say of these three modes, which is the best; in some cases one is to be preferred, in others another. The distance point and the diagonals are the most used in sketching from nature, as it is seldom found necessary to construct a plan, the general outline and position of the vanishing points being taken at discretion. In minute parts of a drawing, the use of the point of distance is valuable, as correctness is more readily attained, and it saves much trouble where a perspective line is required to be divided into a number of equal parts, to use the point of distance instead of visual rays, as will be seen on the line drawn from I (on a), to the vanishing point H. Suppose that portion of the line from I to m, required to be divided (perspectively) into four equal parts : draw an indefinite horizontal line from and set off four equal parts at w, 0, p, q; from q draw a line to the horizontal line at u ; these lines drawn from 0, p, to u, will give the perspective positions of these points on Z, m. The reason why the distance point is more convenient for this purpose than the visual rays from a line on the plan, is, first, that you may place your distances on the horizontal line at discretion, and secondly, that by being able to get them wider apart, correctness is more easily attained. Suppose the distance chosen to have been a trifle more than from I to n y as from I to r, the horizontal line would extend to u, and the point of distance must be found by drawing a line from u through m to the horizontal line at v, and lines ruled from the intermediate points r, s, t * The diagonal lines may be used for finding the positions of other perpendicular lines besides the middle line n, as shown in the First Part, Prob. IV. Plate 5. 134 PERSPECTIVE FOR STUDENTS. to the point of distance v,* will intersect the line I m in the same points as those drawn from the points w, 0, to the point of distance u. It may be well here to notice, that from any point on a from which a line is drawn to the vanishing point, the point of distance may as readily be determined as from the point (1) chosen ; or that the point of distance being fixed from the real geometrical length of the line R, measurements may be made on any other line, and the same point of distance made use of ; as if we required to divide the perspective line Jc in half, we have only to measure off on the ground line to the right of the point 2, tlie geome- trical half of the line k of the plan, and a line ruled from it to the point of distance s, would intersect the line K in the middle ; this is clearly shown in the geometrical width of the first arch on the line E and the ground line, Fig. 1, Prob. VI. Part I. In the second problem, Part I., the student could have no difficulty in finding the positions of the points 3 and 4 from a plan ; and as the near edge of the chess-board is on the ground line, and therefore up to the plane of delineation, the line 1 2 has only to be divided into eight equal parts to get the divisions of the squares. It must be evident in this figure, that the point of distance is the readiest way of determining the perspective positions of the points from a to g; if these were to be found by means of visual rays, it would be necessary to divide one of the sides of the plan into eight equal parts, to draw a visual ray from each to the ground line, and from each intersection draw a perpendicular line to intersect either the line 1 — 3 or 2 — 4 ; whereas in the manner adopted in Prob. II. (the point 3 having been found by a visual ray), the point of distance is determined by a line from 2 through 3 to the hori- zontal line, and the intermediate points between 1 and 3 are found by one operation. * This point is out of the picture as well as the vanishing points, but it would be found on the horizontal line by continuing the line u m v up to it. PERSPECTIVE FOR STUDENTS. 135 In Prob. X. Part I. we pointed out the mode (pp. 56, 57) for finding the perspective width of recesses, leaving the first step, the distance of the line 2 from 1 to be determined by eye ; in this figure (27) we shall show with what readiness the depth of the recess may be determined by rule. Let v on the plan represent the plan of the recess ; we shall then require the perspective width of from w to 11; to ascertain which, draw a visual ray from w intersecting the ground line at and from x draw a perpendicular line across the front of the house ; the perpendicular from d is the line 1 of Prob. X. Part I., and the perpendicular from x the line 2 of the same. In this figure (27) we have not introduced the top and bottom lines of the windows, as the manner of proceeding for drawing these is fully described in the directions given for drawing Prob. X. Part I. We have merely shown how the line 2 (Prob. X.) is to be found by a visual ray from a plan ; that being determined, proceed as described, p. 56, Part I., from the corner of the window 4. The same remarks we have made in comparing Fig. 27 with the first problem in Part I., will apply to other plates in the same part ; thus, in Fig. 1 , Prob. VI., if the plan were given so as to fix the position of the vanishing point and determine the distance of the line d from a, the width of the piers and arches, and the intermediate points required for drawing the curves, are as readily found by means of a point of distance as by drawing visual rays to the plane of delineation. The readiest way of drawing this figure, would be to find the width of the arches and the middle line between their sides, by the visual rays, and find the points for the curves as described in Fig. 2, Plate 7. If in addi- tion to what is represented in Prob. VI., the thickness of the arches was required to be drawn as in Prob. XI. Part I., the thickness shown from A to a (Prob. XI.) would be determined from a plan, in a way similar to finding the perspective depth of the recess 11 to w in Fig. 27. 13G PEftSPECTIVE FOR STUDENTS. In the diagrams introduced in Part II., none have been given for the representation of curves in perspective ; ample information has been given to enable the student to construct any plane rectilinear figure in perspective; and as rectilinear figures must first be constructed in order to find intersecting points through which the curves are to be drawn, it was considered that the introductory observations and subsequent examples in Chap. III. Part I., were quite sufficient to enable the student from a plan to draw a circle in per- spective ; the geometrical figure required for so doing, being only a few straight lines intersecting one another at certain points, and all within a square. There are a variety of geometric curves, such as the ellipse, parabola, &c. &c, that, if the mode for geometrically constructing them accord- ing to the rules laid down in works on practical geometry are known, are as easily put in perspective as the circle, although a greater number of lines may be required. These curves are met with in arches, roofs, mouldings, &c, and as we before said, if the manner of constructing these figures geometrically is understood, they are readily put in per- spective. We will introduce one example by putting a semi-elliptic arch in perspective. Fig. 29. The rule for drawing this geometric curve is to be found in Nicholsons " Practical Geometry it is very simple, and produces a good line. It must be understood that to draw PERSPECTIVE FOR STUDENTS. 137 this figure on a large scale, it would be necessary to take, in proportion to the size it is to be drawn, an increased number of points ; four points are very few to get a perfect line, but are quite sufficient to illustrate the principle on which this or any other curve may be represented in perspective. It is superfluous to draw any plan for this figure, the paral- lelogram containing it being drawn in perspective as any other parallelogram would be ; we therefore premise all that preparatory work to have been gone through, and proceed at once to the representation of the curve. The geometrical divisions on a must be carried to the line B, and their per- spective positions found on c by means of the point of distance d on the horizontal line, and from c, these points must be brought to the line a* the representation of A in perspective. The divisions on the line e must be put on the line 0, by ruling to the vanishing point from e through e to it ; this will give all the points requisite for drawing the rectilinear figure in perspective ; and by drawing from / to the points on the perpendiculars on each side of the paral- lelogram, and from g through the divisions on lines up to those from / to the divisions on the sides, similar to the geometrical figure to the left, all the points requisite for drawing the curve will be evident ; the rectilinear figure to the right being the perspective representation of the rectilinear figure to the left. Our limits do not admit of introducing any great variety of figures ; indeed the object is only to point out the princi pies on which perspective drawings are to be made from details of individual parts. In Prob. VIII. Part I. we have given a figure by which the shaft of a column, and conse- * It would be a shorter process to continue the line a, and there place the geometrical divisions (as on b) ; by which proceeding, the divisions got by the point of distance would come at once on a. We have taken the Line b, because, being obliged to leave the lines required for finding the positions of the points, the finding them from a continuation of the line a would have created a confusion with the other lines. 138 PERSPECTIVE FOR STUDENTS. quently a series of shafts of columns, may be drawn ; fre- quently the shafts of columns are of a less diameter at the top than at the bottom ; to represent such a shaft in perspec- tive, it would require only to construct a perspective square within the top square e (see Figs. 6 and 7, Plate 13, Part I.), the same width as the diameter of the top of the shaft, draw the circle within it, and from the extremities of the bottom draw lines to the extremities of the top, similar to the lines s and t, Prob. VIII. In the forms of the roofs of interiors, we constantly meet with arches crossing each other in a variety of ways. It is as easy to draw an arch in perspective in one direction as another : it is only necessary therefore to fix the points from which the arches spring, ample imforma- tion for doing which has already been given, and the arches, whatever may be their geometrical form, are as easily drawn as in Prob. VI. and IX. The annexed diagram (Fig. 30) Fig. 30. is an example of the effect pro- duced by the intersection of arches. It would be super- fluous to show how these per- spective arches were construct- ed, as it would be only a repe- tition of preceding examples ; the points from which the curves spring are similar to 1, 3, 6, 9 of Prob. VII. Part I., the arches springing from 1 to 9 and 3 to 6, instead of from 1 to 3 and 6 to 9. Domes vary con- siderably in their apparent forms, according to the change of position from which they are seen, and to the experienced eye a want of perspective knowledge is easily detected in their representation. There is little difficulty in drawing in perspective any form of dome, provided the student under- stand thoroughly how to draw the geometrical figure, as we will show by a reference to Prob. V. Part I., and Fig. 29, just given. Let us suppose the form of the dome to be that given in Fig. 29, springing from eight points, and we had PERSPECTIVE FOR STUDENTS. 139 drawn the plan of it similar to the nearest perspective circle, Prob. Y. First draw a perpendicular line from the perspective centre of the circle (the intersection of the diagonal lines), the height of A F, and on the line 4 — 2 construct a geo- metrical figure similar to Fig. 29 ; then, as described in Fig. 29, draw the geometrical figure in perspective over each of the lines 1 — 3, 5 — 7, and 6 — 8, as bases representing the line a, and the result will be an accurate representation of such a dome in perspective, as was described. Irregular curves may be represented in perspective in the same manner as described for Fig. 29, constructing your own rectilinear figure about the irregular curve to get a number of inter- secting points in it, and putting this figure in perspective; this would be required in drawing the leading lines of leaves in a Corinthian capital. Any spiral from the volute of an Ionic capital would prove an excellent example for the student's exercising himself on the principles for representing curves in perspective. CHAPTER VI. At the commencement of Chap. Y. p. 107, we remarked that the mere outline of the ground plan of a building would be insufficient as a plan from which to make a per- spective drawing, and that we require for this purpose a series of plans made from horizontal sections of the various parts wherever any change of form occurs either as a pro- jection or recess ; thus in the projections of roofs, pediments, cornices, mouldings, &c, the form and extent of the pro- jection must be drawn on the plan before we can put it in perspective. Fig. 31, p. 141, represents the plan (a), eleva- 140 PERSPECTIVE FOR STUDENTS tion (bJ, arid perspective representation (c), of a square pillar btandmg on a cube, with a projecting top, or capital ; the station of the spectator is marked at ©, to which point visual rays have been drawn from the three corners of each of the squares or the plan that are visible, the inner square being the plan of the shaft of the pillar, and the outer square the plan of the projection (the projection of the base and the capital being the same), and from each of the points of inter- section a, 5, c, d, e on the ground line of the picture, a perpen- dicular line has been drawn ; the point 2 has been brought to the ground line at /, and a line drawn from / to the vanishing point D, gives the perspective position of the point 2 of the plan at 2 ; the cube forming the base of this figure is drawn as Fig. 23, only as the top of it is above the eye of the spectator, only the outer edges of it are visible. The perpen- dicular line from /, by which the perspective height of the base was determined at 7^, must be continued up, and the geometrical heights j k marked on it from the elevation, from each of which points a line must be ruled to the vanishing point d ; the intersections of these lines with the perpendicu- lars drawn from the points c and a, will give the perspective positions of the points Z, and m of the elevation, and per- spectively perpendicular over the points 1 and 2 of the plan ; from the points^' and k lines must be drawn to the vanishing point E, their intersections with the perpendicular drawn from e determine the perspective positions of the points n and o perpendicularly over the point 3. Draw a line from the point m to the vanishing point E, and from o to the vanish- ing point D, intersecting each other in the point p, then m, />, o would be the representation of the under surface of the- slab or capital on the top of the square pillar, per- pendicularly over the points 2 — 1 — 4 — 3 of the plan. On this perspective square we have now to represent the inner square of the plan in perspective, the top of the pillar on which the square slab just drawn stands ; continue the line 142 PERSPECTIVE FOR STUDENTS. 5 — 6 up to the ground line at q, from which draw a perpendi- cular line, and from the elevation set on it the geometrical height of the pillar at r, from which point draw a line to the vanishing point d, the intersection of this with the perpen- dicular from c gives a point, s 9 perpendicularly over the point 8 of the plan ; its intersection with the perpendicular from b, gives a point, perpendicularly over the point 5 of plan ; from s draw a line to the vanishing point E, its inter- section with the perpendicular line from d gives a point, perpendicularly over the point 7 of the plan, and completes the perspective representation of the elevation b from the plan a required. The mode employed for finding the positions of the points s and t by setting up the geometrical height of the pillar at r, is perfectly correct, and serves excellently as an exercise on our previous examples ; but a much readier and equally correct mode of proceeding would be to find their position by means of a diagonal line between m and o; the points t and u being perpendicularly (that is, perspectively speaking) over 5 and 7, the diagonal m — o must give these points in its intersections with the perpendicular lines from b and d. If the points t and u had then been determined by the diagonal m — o, the lines s — t and s — u would have been drawn on a different system ; from the vanishing point D a line must have been ruled upwards through £, and from the vanishing point e a line ruled through u to intersect the last drawn, which would be in the same point on the perpendicular drawn from c, founol by the visual ray from the point 6.* Any additional projection may be put in perspective by * The visual rays drawn from all the points, 2, 6, 8, 4, are in the same line, and consequently the perpendicular line drawn from c answers for the perpendicular angles of any number of parallel squares when the visual ray is in a direct line with a diagonal ; had the station of the spectator been either to the right or left of the position in which we have placed it, the angle j Jc of the slab would not have been perpendicularly over the angle s of the pillar. PERSPECTIVE FOR STUDENTS. 143 drawing it iirst on the elevation, and afterwards tlie horizon- tal section of it on the plan ; thus narrow lillets. such as are constantly placed on pillars a little below the capital, may be represented in perspective with very little trouble, on the same system as was employed for drawing the base and capital : — such as the one we have drawn on the elevation and introduced on the plan with dotted lines.* It is best generally in drawing the plans from which per- spective drawings are to be made, to draw the largest sur- face first, whether it stands on the ground, or is the section of some projecting part over it ; we have, however, in the figure before us, departed from this rule, in adding to the representation the projecting piece round the lower part of the cube on which the pillar stands. This is done to show the student that he must occasionally add to his plan from the elevation as he proceeds : thus the width of this pro- jection is taken from the elevation and set on the plan out- side the outer square, 1, 2, 3, 4, already drawn, and the pro- jection is put in perspective by exactly the same process as the cube standing over the square 1, 2, 3, 4. In the plan of this outer square only two sides have been drawn, as they give the three points that are required : the other two sides it would be a waste of labour to introduce. Let us suppose that instead of the square pillar standing on the cube of the base, there stood a circular column, the diameter of which is the same as the width of the square 5, 6, 7, 8 ; from the centre of the plan describe a circle to represent the plan of the column within the square 5, 6, 7, 8 ; from the point u in the perspective representation draw a line to the vanishing point d, and from the point t draw a line to * This fillet we have not introduced in the perspective representation, as the lines necessary for so doing would interfere with those we shall require for another illustration ; and, as we have observed before, we have not the advantage of being able to erase our lines as we proceed. It may- be done in the same way as a projection we are about to draw round the base. 144 PERSPECTIVE FOR STUDENTS. the vanishing point e ; the intersection v of these two lines gives the tourtb point in the perspective representation of the sguare 5, 6, 7, 8 at the height r of the elevation. The student must now turn back to Prob. VIII. (facing p. 45, Part I.), and refer from this figure (31) to that problem in the fol- lowing description. From the point the intersection of the circle with the diagonal 5 — 7, draw a line parallel to 5 — 8 up to the line 5 — 6 ; from this point draw a visual ray inter- secting the ground line at x ; from x draw a perpendicular up to the line t — v at y. From the vanishing point D, through y, draw a line to intersect the diagonals t — u and s — vj where this line intersects t — u it gives a point corre- sponding with the point 2 of the diagram, Prob. VIII. ; where it intersects s — v it gives a point corresponding with 8 of the diagram ; from each of these points draw a line to the vanishing point e ; the intersection on t — u will give a point corresponding with 6 of the diagram, that with s — v a point corresponding with 4. From each of the vanishing points d and e draw a line through the intersection of the diagonals t — u and s — vj where the line drawn from e inter- sects the line u — it gives a point corresponding with the point 5 of the diagram, Prob. VIII. ; where it intersects the line s — t it gives the point 1 of the diagram. Where the line drawn from d intersects the line t — v it gives a point corresponding with the point 3 of the diagram ; where it intersects the line s — u it gives the point 7 of the diagram. Here it will be seen that we have the eight points required through which to draw the curve of the top of the circular column in perspective, without the necessity for drawing the whole figure of the diagram, Prob. VIII., on the plan : the points 6, 8, 2, 4 being all determined from the single point and the points 3, 5, 7, 1 from the intersection of the diagonal lines t — u and s — v; it was even superfluous to draw in the plan the whole of the circle ; marking from the intersection of the diagonals 5 — 7 and 6 — 8 the length of a radius on the diagonal 5 — 7 at w would have been quite PERSPECTIVE FOR STUDENTS. J 45 sufficient. The curve may be drawn through these points, and the sides of the column drawn down similar to the lines s and T from the curve E, Prob. VIII. Part I. In the foregoing illustration (Fig. 31) we have shown by a very simple figure how the projections of any original object are represented in perspective from a plan introducing the sections of the projections where they occur, all of which, save the circular column, are of the same form, viz. squares ; we now present the reader with an example admirably adapted not only to illustrate the same, but also as an excel- lent exercise for the student on all the examples given in the two parts of this work. The student on looking at this figure must not be alarmed at its apparent intricacy : there is not a line in it but what has been explained in preceding drawings, and if each portion of the figure be examined separately, and looked at as a distinct figure, all intricacy will vanish : the square block forming the base is drawn by the same rules given for the cube in previous examples ; the triangular solid that stands on it is equally simple ; the directions for drawing the half-circle on the top of this last figure were explained in the First Part (Prob. V. &c.) ; the blocks forming semicubes are as simple as the earliest examples we have given in this Part ; and the mode for drawing the semicircular forms made by the shaft passing through these blocks was amply illustrated in Prob. VIII. The projecting parapet and pier standing on it is but a variation of the last figure, and if we only hide with a piece of paper all the under part, it will appear equally simple. It is the imperative necessity for our leaving all the lines required for constructing our figure that makes them appear complicated ; whereas the student in his progress will be able to erase the lines that are used in the construction of one figure before he proceeds to the next, by which his pro- ceedings will be divested of all confusion of lines. Before commencing this figure, the student must recollect that in our progress we have frequently observed, that for the pur- Perspective, rj 146 PERSPECTIVE FOR STUDENTS. pose of instruction we have been compelled to introduce more lines than were absolutely required for the construction of the figure, and also we have in numerous cases pointed out that a result equally correct is to be obtained by a variety of modes of proceeding ; therefore in the construction of a figure like the present, consisting of a combination of parts, dissimilar in form, one part may be drawn by means of visual rays for finding the positions of the various points, and the points requisite for drawing the next may be deter- mined by that previously drawn ; the mode that produces a correct result with the fewest possible number of lines is always the most desirable. In this figure, for the advantage of more clearly under- standing the references, we have placed a plan both under the elevation and perspective representation, the manner of drawing which we are about to describe ; and in order to afford every facility to a perfect understanding of the figure, every alternate form is drawn with dotted lines. The origi- nal object, the buttress of a bridge, is viewed from a recess on the bridge looking over the parapet, which necessarily causes the horizontal line to be placed very high. This position is chosen, as it presents a larger surface on which to represent the several figures. We will in this representation take each part of the but- tress separately, treating each as a distinct figure, and before the student commences his perspective drawing, he should on a large scale copy the elevation and plan below it, care- fully marking all the letters and figures for reference, draw- ing on the plan for constructing his perspective figure each part as it is described ; he will also find his progress through die drawing much simplified by putting in each figure when completed with ink, and rubbing out all the superfluous pencil lines. We commence then with the square base marked A. It is quite unnecessary to give any directions for drawing this figure, as it would be but a repetition of what has been already fully explained ; all the lines, however, PERSPECTIVE "FOR STUDENTS. 147 Fig. 32. H 2 148 PERSPECTIVE FOR STUDENTS. that were used for drawing the perspective form are left on the representation for the advantage of the student.* The second, which is a triangular figure, might have been drawn by finding the vanishing points from the lines 1 a and b a of the Plan ; but as the perpendicular planes over these lines are the only planes standing in these directions, the triangu- lar figure may be drawn by a much shorter process. From the point c t draw a visual ray to find the position of c % on the top of the perspective square a, from which draw a line parallel to the ground line across the square, which will give the point d on the line 2b; from d draw a long per- pendicular line, as the position of this point will be required in every portion of the figure ; from a draw a perpendicular line to e (the geometrical projection of this triangular figure), and from e a line to the vanishing point, the intersection of this with the line c d gives the position of the point a on the plane a ; draw the lines 2 a and a 5, which will give the perspective form of b of the Plan on the plane A. From each of the points 2, a, 5, draw an indefinite perpendicular line, bring from the elevation the point 3 to the line of projection j k, and from it draw a line to the vanishing point ; from the point of intersection d on this line draw a horizontal line to the perpendicular from a ; join the points 3 a and a b, * The student will bear in mind, that the plan being drawn below the ground line, the figure is reversed. f In order to curtail as far as possible the quantity of lines that are unavoidable in making a perspective drawing, we have drawn this figure in parallel perspective, and the plane of delineation right up to the nearest face of the base figure; by so doing, we are enabled to get the measurements of the heights on the line J k (which may be called the line of projection) of the representation direct from the same line in the elevation. X The letters for reference are made on the plan of the elevation, but the lines representing the visual rays are drawn from the corresponding points on the plan under the perspective representation. The letters in the perspective representation indicate points that are perpendicular over the points, with similar references in the plan at whatever height they may occur. PERSPECTIVE. FOR STUDENTS. 149 which will complete the perspective drawing of the second figure. To draw the form of the third figure on the plane b, we must first find the positions of the points f and h on the line 3 b. This is done by visual rays drawn from these points from the plan to the ground line, and the perpendiculars from the points of intersection will give the points / and h on the line 3 b. Continue the horizontal line to the right of the point 3, the length of the radius of the circle (d f of the Plan), and from its extremity draw a line to the vanishing point ; then from each oi the points / and h draw a hori- zontal line to meet the last drawn at g and j ; this will give the perspective half-square in which to describe the semi- circle. Draw the semi- diagonals d g and d j j the semi- diameter is already drawn by the line da; it remains only to find the perspective positions of the points of intersection made by the curve on the semi-diagonals to enable us to draw the figure ; from k (on the Plan) draw a visual ray to the ground line ; a perpendicular drawn from the point of intersection will give the perspective position of the point k on the semi-diagonal d g ; a line from this point k to the vanishing point will give a corresponding point on the semi- diagonal d j. The curve should now be drawn through the several points, which will be the perspective form of the semicircle c of the Plan on the plane B. The fourth, sixth, and eighth figures are all of the same form, being projections of half-cubes. It will be seen, on referring to the plan and elevation, that the perpendicular angles of these figures are over the points/, g, k,j; the posi- tions of these points having been determined on any one plane, their positions on any other will be perpendicularly over (or under) those already found ; therefore from each of the four points /, g, h, j on the plane b draw up an indefinite perpendicular line, then bring each of the points 4, 5, 6, 7, 8, 9, to the line of projection for the perspective representa- tion, and from each of the points draw a line to the vanishing point ; the lines drawn from 4 and 5 at their intersections 150 PERSPECTIVE FOR. STUDENTS. with the perpendicular from /, determine the height of the perpendicular angle of the half-cube d standing over f ; horizontal lines from these points of intersection to the per- pendicular line from g determine the height of the angle over g ; from the points of intersection on the perpendicular from g, draw lines to the vanishing point, their intersections with the perpendicular from j determine the height of the angle standing over j ; from the highest intersecting point on the perpendicular from j draw a horizontal line to meet that drawn from 5 to the vanishing point, which will complete the perspective drawing of the half-cube d ; the drawing of the two other half-cubes is a mere repetition, substituting in the directions above given the figures 6 and 7, or 8 and 9, for 4 and 5.* The process for drawing the semicircles on the planes D, E, and f is the same as that for drawing the semi- circle on the plane b ; the positions of the points I and m (of the plan) must first be found on each of the lines drawn from 5, 7, and 9 to the vanishing point ; we must therefore draw visual rays from these points I and m on the plan to the ground line, and draw up perpendicular lines from the points of intersection ; these will give on the lines drawn from 5, 7, and 9 to the vanishing point the perspective posi- tions of the points I and m on each ; the position of the point d is already determined by the perpendicular drawn from d on the plane a ; draw then from each of the points I and m a horizontal line across the several planes. From n on the plan draw a visual ray, and from the point of intersection on the ground line a perpendicular, which will give on the hori- zontal lines drawn from m points on each of the planes D, e, and F, corresponding with the point n on the plan ; from the vanishing point through the points n\ draw lines to meet the * The three half- cubes are treated as one figure, also the shaft passing through them, all the points required for drawing the semicircles on the upper planes of the three half-cubes being determined by one process. f From either of the points n or o, a visual ray might have been PERSPECTIVE FOR STUDENTS. 151 horizontal line from Z, which will give the points on each plane corresponding with the point o of the plan ; draw in each figure the lines d n and d o, on which we have to find the points through which to draw the curve. From^p (on the plan) draw a visual raj, and from the point of inter- section on the ground line a perpendicular, which will give the perspective positions of the points p on each of the semi- diagonals do; from each of the points p draw a line to the vanishing point, which will give a corresponding point on each of the semi-diagonal lines d n. All the points being determined through which the curve passes, the curve should be drawn on the respective planes, and a perpendicular line from the extremity of each curve to the right to meet th projection above it. We will pass by for the present the projecting parapet, and proceed to the pier standing on it ; the perpendicular angles of the base of this figure, as may be seen by the plan and elevation, are perpendicularly over the angles of the three half-cubes, and must consequently come on the perpendicu- lars drawn from the points /, ^, and j y on the plane b ; therefore bring the points 11 and 12 of the elevation to the line of projection, and put the base of the pier in perspective, according to the directions given for the half-cube D. The perpendicular angles of the portion L of the pier not project- ing so far as the angles of the base, the lines representing them must be found by visual rays, which must be drawn from the points q, r, and s of the plan to the ground line at drawn to have determined their perspective positions ; the point n was chosen, and the point o found from it by the vanishing lines n o, to avoid confusion. These points n and o might have been determined in a different manner, by drawing semi-diagonal lines from the points d to the corners of each of the planes d, e, and f ; the intersections of these semi-diagonal lines with the horizontal ones drawn from / and m would be in the same points n and o ; this indeed would prove the readiest way of determining these points, as it would at the same time have given the semi -diagonals d o and d n, which are required for drawing the curve. 152 PERSPECTIVE FOR STUDENTS. ?«, and 0, and perpendicular lines drawn from each ; carry the point 13 to the line of projection, and from it draw a line to the vanishing point, the intersection of this with the line drawn from t will be the point q (perpendicularly over the point q of the plan at the height marked 13 of the elevation); from q draw a horizontal line to the perpendicular from this will give the perspective position of the point r of the plan at the height marked 13 ; from r to the vanishing point rule a line to the perpendicular from «?, the intersection will give the perspective position of the point s of the plan at the height 13. The sloping lines from the points r, and s must be ruled to the top of the angles of the base of the pier. The line from the base of the projection 14 must be drawn pre- cisely in the same way as the lines of the base of the pier from 11 and 12, the points of this projection being perpendicularly over the points /, g y h,j; the lines got from 15 and 16 similar to the line from 13, and the projecting angles from the ex- treme points of projection. The plan of the parapet on which the pier stands, from our limited space, we cannot introduce so as to get our points from it by visual rays ; we have, however, in very faint dotted lines on the plan under the elevation, shown what the projection is, sufficiently to understand our manner of drawing the perspective representation ; the points 10 and 11 are placed on the line of projection, and the horizontal lines from them continued to the right to w and their geometrical length ; through each of these points, in a direction towards the vanishing point, we have ruled lines to the right and left ; from the point d on the plane of the top of the parapet, through the angles of the base of the pier, draw lines to meet the line drawn through x 9 to determine the corners of the projection in front of the pier (see the dotted lines in the plan) ; from each of the points of intersection on the line through x draw a parallel line to meet the continuation of the base line of the pier ; the intersections determine the points from which the projection commences. The under line of PERSPECTIVE FOR STUDENTS. 153 the projecting parapet showing its thickness, it is unnecessary to describe, the several points lying perpendicularly under those of the upper one. We have taken considerable pains to make the directions for drawing this figure so clear as to enable the student to draw any other figure composed of a variety of parts of dis- similar forms by a reference to it. The small space afforded by a page of this work precludes the possibility of introducing more than one buttress in the representation ; in the single one given, the lines are necessarily so close together that great care is required in attending to the references ; we wish, however, to point out how any number of these buttresses, forming the piers of a bridge, may be drawn in succession, with the arches between them, with the fewest possible quan- tity of lines ; this we will explain by referring to Prob. VI. 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