332 PHILOSOPHICAL TRANSACTIONS. £aNNO 1753. 



by F. Frisi, I have too much relied on the certainty of observations, and at- 

 tempted to disparage Sir Isaac Newton's discoveries. 



In the first place, I will ask F. Frisi if before the operations, which I de- 

 pended on, were performed, I could establish any thing against their agreeing, 

 or not, with Sir Isaac's proposition about the same matter ? 



He perhaps will answer, that my remark of the 69th art. " But if the dia- 

 meters were found undoubtedly in a greater ratio to one another than 230 to 

 231," imports that I was not thoroughly convinced, that what care soever would 

 be taken by the gentlemen sent into Peru, they never would be able to measure 

 their degree with a sufficient exactness, to conclude, -from its length, compared 

 with that of the other degrees, whether the diameters were in a greater or less 

 ratio than 230 to 231 ; and consequently he will think, that my being in sus- 

 pense about it was an offence against Sir Isaac's theoretical determination. Then 

 I request F. Frisi to tell me, why he is so good as to commend operations so void 

 of use, as those which tended only to discover what was demonstrated before, 

 and needed not to be confirmed, since it could not be invalidated. 



Perhaps F. Frisi, in representing me as depending too much on the observa- 

 tions, relied on these expressions of the 69th art. ' As the measures of the gra- 

 vity cannot agree with the supposition of the homogeneity :' and I confess, that 

 it seems to me impossible to reconcile the great number of all the measures of 

 that sort with the table which follows the homogeneity. For the simplicity of the 

 means made use of in the performance of those measures cannot admit the errors, 

 which should be supposed to bring them to Sir Isaac's theory : but as this theory 

 is founded on the homogeneity, which is only a mere supposition ; and as he has 

 himself suspected, in his second and third edition, that the internal parts of the 

 earth might be denser than those towards the superficies, I do not see how I 

 oppose myself to that illustrious philosopher, when I assume the same hypothesis 

 as he does. As I shall use all possible endeavour to understand F. Frisi's mean- 

 ing, I hazard this conjecture. Seeing that I thought favourably enough of the 

 exactness to be obtained in astronomy, when observations have been already 

 made in great numbers, and with all possible care, to suppose them fit to let us 

 know, whether the diameters are in a greater or less ratio than 230 to 23 1 : and 

 being informed afterwards, that the operation made in Peru led those who have 

 made use of it to imagine the spheroid flatter than the homogeneous, he con- 

 cludes, that I cannot help thinking like them, and accordingly indulges himself 

 in exposing how much I over-rate the validity of observations, and how little I 

 know the submission due to a proposition of Sir Isaac ; which, I must say by 

 the bye, that great man has never himself given as impossible to be opposed by 

 experience. But yet I would ask of F. Frisi, why he will guess at my sentiments. 



