TO CONVERT ROUND MEASURE INTO SQUARE. ]5J 



fervention of convex orconcave ienfes, the apices of the dif- 

 ferent cones of rays would fall either before or behind the 

 retina. He fupports his theory by experiments which he tried 

 on fhort and long-fighted perfons ; and quotes the pauage from 

 -Ariftotle, in which he points out the difference between the 

 myops and the preibytes. 

 Feb. 12. 



II. 



Conftruclion of a Line in a Circle, nearly equal to the Side of a 

 Square of the fame Supe?ficies as that of the Circle itfelf. With 

 Bemarks on Pendidium and other Obje&s. By Mr. J. Whitley 



BOSVVELL. 



To Mr. NICHOLSON. 

 SIR, Feb. 9, 1805. 



jlilAVlNG often found a difficulty in computing the preffure Introdu&iom 

 of fluids in tubes and cylindrical vefiels, from all the calcula- 

 tions relative to the gravities of different bodies, which I was 

 acquainted with, being adapted for cubic meafure, it appeared 

 a vevy defirable matter to rind an eaty method of converting 

 round into fquare meafure, which induced me at different 

 times to attempt it, and as often to lay it afide, from not being 

 able to arrive at any fatisfactory refult. But lately having had 

 occafion to refume this lubject, I have difcovered a method of 

 coming fo very near the truth, that if it (hould turn out to be 

 in reality not fo exa6t as it feems to me, it will ferve fo well 

 for common compulations, and promifes on that account to be 

 of fuch utility, that I am induced to fend it to you for publi- 

 cation, if you approve of it. 



As this fubjeel has been by many looked on as fomewhat To convert 



chimerical, it may be therefore not amils to mention, for thofe round me:l1ur s 



■ * \ _ into fquare. 



of your readers who are not very convenant in geometrical 



ftudies, that a mechanical method of computing fquare mea- 

 fure from round is a very ancient and well-known problem ; 

 but this method being difficult to apply to the infide of tubes, 

 and not capable of being ufed in diagrams or drawings, has 

 made another method rJ this pufpofe is as 



follows : — 



