i8 79 .] 



LESSONS IN DRAWING, ETC. 



85 



utilised by drawing lines at right angles to them to certain points, 

 and measuring such distances as may be required to ascertain the 

 position of such points on the ground. To make this easily under- 

 stood, suppose that line a b, fig. 63, is one of the lines just men- 

 tioned, or that has been drawn (as it really has) for the purpose of 

 measuring from, but drawn square with any other lines previously on 



Fig. 63. 



the plan. We shall draw another line, c d, at right angles to a b, 

 and make the intersection of the two a starting-point. This happens 

 to be near the centre of the carriage-road, and from that point to 

 where the line a b crosses the edge of the drive, is on the one hand 

 10 feet, and on the other 14 feet. Mark this upon the plan on the 

 line between the points measured from. Working up the line a b, 



G 



