82 OPEN AIR GEAPE CULTURE. 



stand from each other, drive in stakes a a at each 

 end, and measuring off 16 feet, drive in other two, 

 B B. The heads of these should be made level with 



Fig. 6. 



the surface of the ground, and headless nails should 

 then be driven into them — the two nails (a and b) at 

 each end being exactly 16 feet apart. Now place the 

 rod on one of the outside stakes, so that the nail will 

 pass through the first hole {a) and drive a peg into 

 the hole in the rod 12 feet from the end. With this 

 peg mark a curve (^), and then placing the end {a) of 

 the rod on the stake b, mark another curve [d) cross- 

 ing the first by means of a pin passing through the 

 hole {d). A line (a d), drawn from a through the cross- 

 ing of these curves will be perfectly square with the 



