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6m 



THE PRACTICE OF FORMING 



BOOK IT. 



CHAPTER IV. 



OF MARKING OUT IMPROVEMENTS ON THE GROUND, AND 

 OF SOME PRACTICAL OPERATIONS OF EXECUTION. 



The first thing necessary, in proceeding to execute any part 

 of a plan, is to mark it out upon the grounds. The judicious 

 and true performance of this depends upon an experienced eye, 

 and a knowledge of practical mathematics, especially geome- 

 try in its various branches. The rules for marking out the, 

 ground plan of a building, garden, or any object containing 

 many regular figures, are perfectly simple ; they are deduced 

 from two well known problems, viz. " Three points not in a 

 straight line being given, to find the centre of a circle which 

 shall pass through them," from which every thing relating to the 

 protraction of circles, ovals, and ellipses, may be deduced ; 

 and " the erection of a line perpendicular to any given one/' 

 to which may be reduced every thing relating to straight lines, 

 squares, and angular forms. The execution of these problems, 

 and every variety between them, is simple*, and needs no com- 



* Those who wish for more ample information on this point, will find it iu 

 Switzer's and Le Blond's Treatises on Gardening, 



