LESSONS IN DRAWING. 





for finding the vanishing point (see page 137): vp2 is tho 

 vanishing \< > tho vanishing point of a b ; 



v B an '^ual rays that in, they arc im 



U nt:S poshing from tho extremities of tho object through tho P v 

 to tho eye. Those linos will indicate where tho point* a, 6, 

 and c would bo depicted on the picture plane viz., at e, f, and g. 



Pig. 69. 



VP... 



extremities of each wall coma clour tofrtttr on the plan* of 

 representation that U, the pictore plane and therefore we da 

 not see the whole extent of the wall a* we ahoold do if we stool 

 parallel to it We will carry oat the snbjeet, and show the walk 

 a* they would naturally appear. To do thfc we mtut meirs a 

 fresh diagram, because, to prerent confusion, we do not wish to 



These visual rays must always be drawn from the extremities 

 of lines, or any especial point which is to be represented in 

 the picture, in the direction of the station point, or eye, but 

 stepping at the picture plane (see Fig. 65) ; afterwards, from 

 e, /, and g, they are drawn perpendicularly. For the reason why 

 they are drawn perpendicularly, we refer the pupil to future 

 lessons on geometrical perspective. Then produce or draw out 

 one of tho lines of the plan, say a c, to meet the picture plane. 

 The point of meeting is called the point of contact, P c. Draw 

 a perpendicular line from the P c to the base of the picture. 

 We will call that P c 2, meaning the point of contact brought 

 down. Join tho P c 2 to V P 2, and somewhere on this last line 

 will be the picture of the object a c represented in the plan. 

 This is determined by the visual rays being perpendicularly 

 drawn to a 2 and c 2 , therefore between a 2 and c 2 is the picture 

 of the line a c ; ::o, for the other line a b, draw a line from a 2 to 

 v P 1, and the visual rays, as before, brought down, will deter- 

 mine the perspective length of a b viz., a 2 o 2 . Perhaps some 



add any more lines to that already given. We recommend the 

 pupil to repeat tho perspective view of the plan in Fig. 65, M 

 given in Fig. 66. In this figure P c and p c 2 represent the 

 points of contact of the line a, c that is, supposing the line were 

 brought to the picture in other words, to touch it. Then, hi 

 this case, it would be represented in the picture its natural sixe, 

 therefore we call the perpendicular lino drawn from PC to P c 2 

 the line of contact, marked L c. Upon this line we always maann 

 and set of heights of objects. Suppose, then, the height of the wall 

 to be marked at r, draw a line from r to v P 2 : ttot will be the 

 top of the wall a c ; draw a line from s to v P 1 ; sm will be the 

 top of the wall a b. Now if we wish to draw the course* of the 

 bricks, we must set them off also upon the line, of contact as we 

 did to represent the top of the walls, and draw them to their 

 respective vanishing points ; also, the perpendicular joints of 

 the bricks must be marked in the plan, and brought down by 

 visual rays in the same way as the ends of the walls were 

 found. We have represented a few of the bricks, leaving the 



reader may ask why wo do not draw the line from P c 2 to v P 1, 

 instead of v P 2. Our answer is, because P c is the point of 

 contact for a c and not a b ; if a b had been produced to the 

 PP for a point of contact, then it would have been right to 

 draw a line from P c 2 in the direction of v P 1. 



All that we have now done in this perspective diagram is, 

 that we have shown tho horizontal retiring length of the base 

 ot the wall each way viz., a 2 c 3 on one side, and a* b- on 

 the other. To have drawn these lines equal to the length 

 of the walls themselves that is, those of the plan would have 

 been a very great mistake, because as they retire the further 



pupil to complete the drawing ; the plan of the door is shown at 

 n o, its height at p. (We will observe, by way of parenthesis, 

 that all heights of objects are marked or set off on the Km tf 

 contact ; all horizontal lengths and breadths are shown in the 

 ground-plan, and brought down by visual rays.) We wfll give 

 one other method of showing the horizontal perspective length of 

 a line or plane, and then leave the pupil to think over and prac- 

 tice all that we have been trying to teach him. Let a 6 (Fig. 67) 

 represent the length of a line to bo shown in uer*ueoti*e at 



a given angle with our position or with the picture plane. Let 

 p s represent tho point of sight, s P the station point, H L the 



