1 82 On some Animadversions on the Trigonometrical Survey. 



servations:" and, as if to add weight to his opinion, and show 

 how adeqnately and temperately he forms his judgement, he 

 observes " that there is ito set (if men more apt to indulge in 

 inaccurate or absurd views tha?i miitfiemciticians ! !" A posi- 

 tion so liberal and demonstrative that he adds, if it "stood in 

 need of confirmation, it would be easy to bring forward some 

 of the most celebrated names both of former and present times 

 in confirmation of it." 



But, happily, neither the reputation of mathematicians nor the 

 true issue of this question depends upon the fiat of D'-. Thom- 

 son. A philosopher of no less celebrity than the Chevalier De- 

 lambre has published some " reflections" on Don Rodriguez's 

 paper, in the " Connaissance des Terns pour I'Anl^X^," from 

 which I shall select a few quotations. 



Speaking of the northern partial arc examined by Don Ro- 

 driguez, and of its indicating a compression approaching to 

 nothing, he says, " I acknowledge that, this last result is ex- 

 tremely destitute of probability; but it is littte probable also, 

 that the same instrument, which had given accurate zenith di- 

 stances at the two extremities, should furnish an error of Jive 

 seconds at the mean station. Besides, it is not fully demon- 

 strated that the curve of the meridian is a regular ellipse, and 

 that the compression which is inferred from two very remote 

 arcs, as those of Peru and Sweden, is the compression which 

 accords with all the intermediate arcs," " The operations which 

 determine the compression do not offer any real satisfaction, and 

 we may yet doubt of the perfect regularity of meridians, as well 

 as of their perfect similitude.". In another place M. Delambre 

 remarks, " that of the eight partial arcs of Colonel Mudge, 

 M. Rodviguez has only exfanined three;" and adds, " it would 

 be curious to see how Greenv.ich and Blenheim accord with the 

 idea that the whole error arises, from the observations made at 

 Arbury." 



Perceiving from these remarks how unwilling this eminent 

 mathematician and astronomical observer was to infer, even from 

 Don Rodriguez's paper, that there existed an error of 4~ se- 

 conds at Arbury Hill, I took an early opportunity of trans- 

 mitting him a copy of my strictures inserted in your publication. 

 I have the satisfaction to know that, vvith the exception of my 

 remarks on the observations at Dunkirk and Chatlllon, to whicli 

 he has replied, he tiiinks. my attempt successnd : he agrees with 

 me, that there can be no such error at Arbury Hill as Don Ro- 

 driguez imagines, and that my comparison of the observations 

 there and at Dunaose with those at Blenheim and Portsmouth 

 has set the matter at rest. 



Here, then, I may with perfect composure take my leave of 



this 



