7 6 



GARDEN DESIGN 



'3 



DIAGRAM 21. 



stream, and have it taut enough to 

 measure by. However, one can gener- 

 ally see across water, and thus be 

 able to stake out a straight line. 

 Suppose the line A B is set to be 

 measured, but an obstacle C D inter- 

 venes ; either water or beds of some 

 frail plant that might be injured by 

 the tape being put across them. (See 

 Diagram 21.) At C put up a line 

 at right angles of sufficient length to 

 clear the bend, and at D do the 

 same, d D being equal to c C, then 

 c d is equal to C D, and the survey 



can be continued again from D. 



Sometimes it is necessary to find the position of a 



point inaccessible to the tape, such as an island or a 



promontory coming from 



the farther bank of a lake. 



Diagram 22 represents such 



a difficulty. The point A 



is known, and P on the 



island across the water is 



wanted. Set up a sighted 



line from A to P, in order 



to lay the tape at right 



angles to A P, giving the 



line A B, which for the sake ,/ 



of accuracy should be run ^-"'"^ 



out rather longer than the DIAGRAM 



