7 5 Numerical InfiruBions 



To plot a Fields whofe Largenefs and Irregula- 

 rity will not permit its being taken at one 

 Station^ 



By the Plain Table. 



Fig. 7^ T ET the irregular Polygon A B 

 L C D E F be fuch a Field, and 

 the firft Station ^t Point G. Your Inftru- 

 ment being placed and prepared, as has been 

 direfted, dired your Index and Sights to A, 

 and draw GA,„mea{ure G A 2 ch. 93 li. 

 cutB, and draw GB, meafure GB 2 ch. 65 

 li. 5 cut C, and -draw G C, meafure GG 

 2 ch. 8 li. 5 cut F, and draw GF, meafure 

 G F 2 ch. 47 li. 5 draw A B, B C, and F A. 



At G direft your Sights and Index to any 

 Point, or Perfon, (landing in any Point, R, 

 and draw G R, meafure G R 5 ch. 46 li. 



Point R is my fecond Station, where, pla- 

 cing my Inftruraent,. I put the Index on the 

 I^ine GR, and move it about, 'til I cut a 

 Mark or Perfon ftanding at G, and ther^ 

 fcrewing it faft, 'tis prepared for taking the 

 reft of the Field. 



Direft your Index and Sights to D, and 

 draw R D, meafure R D 2 ch. 50 li. 5 cut An- 

 gl^E, and draw RE, meafure RE i ch. 83 

 Ji,5 cut F, and draw RF, meafure RF 3 ch. 



25 



