7he PraBice Jart IL 



vtheir' Extremities meet, a$ in drive a Stake, and trace the 

 Lines B D and C which, with A B and A C, will form the 

 Parallelogram-^ BCD. 



The First O bs eryatiok-. 



If the oblong Square were much bigger than this, you 

 „muft then raifc, with the Inftrument, two Perpendiculars 

 upon the Extremities of the Line A B^ according to the 

 Obfervation on the iixth Praftiee, and make each of thofc 

 ■Perpendiculars equal to the Breadth of the Parallelo- 

 gram. 



The .SEiCOiND Observation. 



To draw a perfed Square, the Pradice is the fame with 

 that above, faving that the two Perpendiculars muft be drawn 

 .as long as the Bafe of the Square. 



THE THIRTEENTH PRACTICE. 



To defer ibe^ with the Line^ an Irregular Figure of four Sides-^ 



Suppose the Irregular Figure to be abcd^ from the 

 Points, with the Interval c", defctibe with the Compaffes 

 .an Arch, as c^; and from the Point ^, with the Interval 

 -make another Arch, as dfi meafure the Lengths ab^ wliich 

 fuppofe 25 Fathom, ac pFathom^ bdxi Fathom, and the 

 Cords of the Arches or Diftances from cto ^ 10 Fathom, and 

 from fiodx^ Fathom. Then trace upon the Groimd the Line 

 or Bafe AB o£ 25 Fathom long, and carry from AtoE 

 p Fathom, and from B to F 1 1 Fathom ; plant two Stakes 

 in the Points E and F, and taking a Cord of nine Fathom 

 £x'd to the Stake A^ and one of i o Fathom long fix'd to the 

 Stake E, bring their Ends to meet in the Point C, and drive 

 ^ Stake there : Do the like on the other Side, as upon the 

 Stake B fix a Cord of 1 1 Fathom, and one of 14 upan ithe 

 Stake F, bringing their Extremities together in the Point 

 :and tracing the Lines y4C, CD, DB, you foi;m, TOth.filpie 

 Bafe A the four-fided Figure ,propofed* 



THE 



