250 On Capt. Ross's Reply to Capt. Saline. 



any such error is also provided against by directing the polar 

 distance to be taken out for the time of observation. 



Mr. Meikle lastly mentions a table of this kind, in which the 

 star's polar distance at the time of the pubUcation of the table is 

 erroneous bv 4-0'. The table is in Mackav's Navigation, and 

 the error Is about what Mr. M. has stated it to be. 



But in disingenuously endeavouring to convert this circum- 

 stance into an argument against putting confidence in any tables 

 of the kind, he betrays an aberration from rectitude of intention, 

 which shows that he is not more apt to suspect others, than to 

 give, in his own conduct, cause for suspicion. 



I have now gone through the whole of this gentleman's ob- 

 jections, and at greater length than I oriainally proposed to my- 

 self ; and I hope I have made it apparent that the " errors and 

 delusions " which he has so liberally, so confidently, and so un- 

 ceremoniously ascribed to the writers on navigation, have no ex- 

 istence but in his own imagination. 



Your obedient servant, 



Edward Riddle. 



P. S. — This does not appear an improper occasion to make a 

 few remarks on some observations in page 31st of the pamphlet 

 which Captain Ross has published in reply to that of Captain 

 Sabine. 



Speaking of Captain S. and himself, he says, " but, as we dif- 

 fered on the method of applying the refraction minus parallax, 

 I made no use of his observations — he judging it proper to cor- 

 rect the observed altitude of the sun's limb for thesemidiameter, 

 before he took out the refraction ; and I, being accustomed to 

 apply that correction to the altitude of the sun's limb, before the 

 semidiameter was applied. In the Alexander, printed forms were 

 found according to the former method, which having confirmed 

 Captain Sabine in his first opinion, he continued in this error 

 during the voyage, and therefore neither his latitudes, longitudes, 

 or variation were correct ; and whenever I had occasion to make 

 use of his altitudes, I took them as corrected only for the index 

 error and the dip of the horizon." And he adds in a note, " the 

 printed forms for the present expedition have been altered in con- 

 sequence." 



There is in this statement an apparent inconsistency — Captain 

 Ross says in one place that, for a certain reason, he made no use 

 of Captain S.'s observations ; and in anotlier place he says, 

 " when I had occasion to use his" (Captain S.'s) " altitudes, I 

 took them," &c. It is not, however, on this circumstance that 

 I wish to remark. 



It 



