194 Dr. Gregory's Strictures oil Dan RodrigueX; 



dent, might as easily have been made by Don Rodriguez as 

 by 11) c. 



This gentleman may find still fiirtlier confirmation of 

 the truth of the whole survey, if he will examine the ope- 

 rations by which the meridian of Dunnose is extended to 

 Burleigh Moor, and those for carrying on a new n)eridiart 

 from Black Dov\ n to Delamere Forest~l These, it is true, 

 are not to be found (for what reason I cannot say) in the 

 Philosophical Transactions. But they may be seen in the 

 third volume of the Trigonometrical Survey, published in 

 1813 by order of the Board of Drdnance ; a volunK' with 

 which some of Don Rodriguez's iriends in England are 

 doubtless acquainted. 



As a last corroboration of the whole portion from Dun- 

 nose to Clifton, amounting to <2,'' bO' 23-"38 ; let me add 

 that, when compared wiih the meridional arch of S"" /' \" 

 at Peru, by rneaiis of the valuable theorem investigated by 

 Professor Playfair (Edinburgh'IVansactions, vol. v. pp. 8, 9-) 

 for the comparison of large arcs, it produces ^j-i-^sT- f^^'' ^^^ 

 resulting cujnpression. While Svanberg (o. \ 92, Exposi- 

 tion) gives 3_j-pi^__ for the compression, as dcducible from 

 a comparison of his measure with that at Peru. 



Ihus, we have confirmation upon confirmation, of the 

 correctness of Col. Mudge's operation*, both general and 

 particular ; and of the extreme rashness with which Don 

 Rodriguez has affirmed that " it is verij evident that the 

 izenith distances of stars taken at Arbury Hill are affected 

 by some considerable error." The matter in question might, 

 as you will perceive, have been settled in narrower compass: 

 but the celebrity of the Institution under whose auspices 

 the Don's animadversions are circulated, seemed in some 

 measure to call for a tolerably full reply to his paper. 



For the reply here presented the public must consider 

 me alone as responsible: and I trust that when the two 

 papers have been compared, I shall not be thought to speak 

 incompatibly with the courtesy due to a foreigner, or the 

 respect due to a brother mathematician, when I say that 

 Don Rodriguez has compktehj jud.ed to establish the point, 

 respecting wh^ch he ought lo have felt certain before he 

 commenced his strictures. 



^ Royal Mlliury Academy, OlINTHUS GrEOORY. 



WoolwicI), March 5* \^VX 



XXIX. De. 



