[iv] 



and afcertain their meaning; where there 

 is nothing fyftematic, to lay down a regular 

 planj where the different parts are gene- 

 rally looked on as complete, to mark the 

 deficiencies, and mow that there is much 

 wanted 5 where the means of improvement 

 are unknown or neglected, to point out 

 the only road that can lead with certainty 

 to it 5 where there are few experiments to 

 build on, to relate fome, and on thefe to 

 lay a foundation for more; where the 

 reafonings are, in general, fo very unphi- 

 lofophical, to fettle fome fund for difcourfe 

 and argument; where the proper helps 

 have not been called in, to make ufe of 

 thefe, and introduce a new fcience to the 

 affiftance of this art ; in fhort, where there 

 is but little afcertained, to fix fome general 

 principles on which the artift may depend : 

 this is the defign of the following papers. 

 That no more has been done, will be 

 moft readily excufed by thofe who are beft 

 acquainted with the difficulty of the un- 

 dertaking. 



A 



