Preparing for the Prefix 



GEOMETRICAL and GRAPHICAL ESSAYS* 



CONTAINING 



I. A feleft Set of Geometrical Problems; amongft the fe are fome very curious 



ones for dividing Lines and Circles with Accuracy. 



II. A Defcription of thofe Mathematical Inftruments which are ufually put into a; 



Cafe of Drawing Inftruments, and many other new ones for Geometrical; 

 Purpofes, 



III. A Defcription of the Inftruments ufed in furveying and levelling of Land. 



IV. A Defcription of thofe Inftruments that have been contrived, to aflift the ArtifB 



in delineating with Accuracy/ and in true Perfpective, the Outline of a< 

 Landfcap?, Building, or any other Objecl. 



Alfo Preparing for the Prefs, 

 An ESSAY on VISION, 



So far as relates to the Ufe of Spectacles, pointing out the Criteria, by which': 

 every Perfon may judge when the Ufe of them will be beneficial, , 

 and how to chufe them without injuring the Sight,.. 



