CHAMBERS'S INFORMATION FOR THE PEOPLE. 



different touch is required for each. In some, the 

 leaves are long and narrow, as in the ash anc 

 willow, and are represented by corresponding long 

 touches ; in others, they are shorter and broader 

 as in the elm and lime ; the peculiar touch being 

 carefully kept up throughout the whole tree 

 otherwise the mixture of elm and willow leaves on 

 one tree will appear unnatural ; yet the mistake 

 is one a beginner is very apt to make. 



The oak is represented by a concave instead o; 

 a convex touch, as at a, in fig. 12, in order to give 



Fig. 12. 



the picturesque crisp touch by which it is charac- 

 terised. Care must also be taken to make the 

 several clusters of leaves appear properly attached 

 together, as at b. 



PERSPECTIVE. 



Perspective is the method by which objects are 

 represented on any flat surface, as a sheet of 

 paper, so that they suggest the true appearance of 

 nature to the eye. It is the basis of the art of 

 drawing, training the eye to discern the visual 

 effects of nature, and giving facility and correct- 

 ness in their representation. 



It is impossible, within the limits of the present 

 paper, to go deeply into the theory of this import- 

 ant subject But the more salient practical points, 

 sufficient for the purposes of the beginner, may be 

 briefly explained. 



Every one has noticed, that as objects retire 

 from the eye, they appear to diminish. The 

 reason of this may be found from the adjoining 

 diagram (13). AB and CD represent two objects 

 at different distances from the eye. Lines drawn 



from their extremities to the retina shew the dif- 

 ference in magnitude of the pictures of them 

 formed there ; cd represents CD ; and the space 

 between ab, AB. It will be seen that AB has a 

 picture nearly double in size of that formed by 

 CD ; that is, it would appear so to the eye. 



It will be observed that the lines or rays pro- 

 ceeding to the eye from AB, slope more than 

 those from CD ; hence they are said to be at a 

 greater angle than those of CD ; and if CD were 

 further removed, the lines would in proportion 



646 



slope still less : hence, as objects recede from the 

 eye, they are said to be seen under a less angle. 

 If we look straight along a street, the horizontal 

 lines of the buildings and pavement appear to- 

 contract and tend towards a point immediately 

 opposite to the eye. Those below the level of the 

 eye, as the lines of the pavement and base-lines of 

 the buildings, tend upward, as AP, BP, fig. 



Fig. 14. 



Those above the eye, as the horizontal portions 

 of doors, windows, chimneys, &c. and the eaves 

 of the buildings, tend downward, as CP. The 

 upward and converging tendency may be very 

 distinctly observed in the long receding lines of 

 the rails on a railway. As a general rule, all level 

 or horizontal lines appear to converge and ter- 

 minate in the horizon, or horizontal line, as it is 

 called in perspective, the particular point in which 

 they terminate being determined by their relative 

 position. 



The same is true of lines that slope, as those of 

 the roofs of buildings ; these also converge : and 

 it is necessary, in copying drawings, when such 

 occur, to note the amount of convergence. Most 

 students are apt to overlook this, and draw them 

 strictly parallel, which is quite true of them as 

 they really are, but not as they appear. 



If a book, a box, or other rectangular object, 

 be placed on a table, 



with two of the sides a 



parallel with the position 

 the spectator, it will 

 be noticed that the lines 

 at right angles to him 

 converge to a point im- 

 mediately opposite the 

 eye, as CF and DF to P, 

 fig. 15. The object in this 

 osition is said to be 

 n parallel perspective. 

 A good idea of parallel 



Fig. 15. 



serspective may be obtained by standing at the 

 nd of a rectangular room, with the back placed 

 lat against one of the end-walls ; the lines of 

 ide-walls at the roof and floor proceed at right 

 angles from the spectator, and tend to a point 

 mmediately opposite to the eye, as in fig. 16. 



But if the back be placed in one of the corners 

 of the room, the lines will not meet opposite to 

 :he eye, as before, but will converge to points in 

 :he horizontal line to the right and left of the 

 position. These will all be inclined to the spec- 

 ator, as in fig. 17, and hence are said to be in 

 angular perspective. 



It is not enough, however, merely to know what 

 >arallel and angular perspective are ; they must 

 >e known in all their various effects, to be of 





