Dr. Gregory's Striclures on Don Rodriguez. IBO 



all. From p. 39 of the same Discours Preliminaire, it ap- 

 pears that three stars only were selected by Mechain at 

 Monljouy, in consequence of the coincidence of the results 

 arising from them. Among the stars rejected was ^ Ursce, 

 because diflerent observations gave a difference of 4". So 

 that the French also detected an irregularity respecting this 

 star. Tliey assign, however, a wrong reason for the fact: 

 for they attribute it to errors in Bradley's table of relrac- 

 tions ; while the truth is, that ^ Ursae is a double star, by 

 no means easy to observe properly. Indeed it appears not 

 only from the observations of Col. Mudge, Sec. Imt from 

 those of Dr. Herschel, (Phil. Trans, vol. Ixxii. New 

 Abridgement, vol. xv,,) that both ju. Draconis and ^ Ursoe 

 are double stars ; that, of the former, the two constituent 

 stars appear equal, both white, and not easily distinguish- 

 able, and at the distance of 4'"35 from each other, mean 

 measure; and that, of the latter, the tw'o are considerably 

 unequal, and the largest difficult to bisect. Hence, Her- 

 schcl's observations completely confirm those of our trigo- 

 nometrical surveyors. See also the Catalogues of VVollas. 

 ton and Bode. 



Let us next inquire how far Major Lambton's observa- 

 tions, which Don Rodriguez also seem* to delight in eu- 

 logizing, deserve to be preferred to Col. Mudgc's. From 

 p. 356, vol. X. Asiatic Researches, we learn thai the Major's 

 observations upon a Serpentis were 14, of which two were 

 3° 57' 3-"3& and 5° 56' 53 "98, furnishing a difference of 

 9"3 ; more than duuble the difference that has been found 

 in the English observations of which the Don complains ! 

 At p. 357 again, we have a regi^te^ of sixteen observations 

 upon V AqiulcC, of which two differ by Q'"n. At p. 358, 

 we have eiirhleeu observations upon Atair, of which two 

 differ by 5*"o8. There are alsr) some other paljjable dif- 

 ferences in Major Lambton's results, as deduced from 

 different stars. The greatest is between Atair and Aiarkab; 

 being o-"4S. Atair, from the number and agreement of 

 its observations among thcm-clves, should be correct in 

 zenith distance; y^i it gives the latitude of ihe station,, 

 Dodagooniah, leis by 3'"4 than the mean of the nine stars 

 employed by Major Lambion exhibits it : and the latitude 

 found from a mean of tiic four northern stars is 2 "04 

 greater than the latitude found from a mean of the five 

 gouthcrn stars. Discrepancies of more than 4" may like- 

 wise be frequently found in the observations recorded in 

 vol. viii. of the " Jlcsearches." Most of them are probably 



in 



