214 OCCULTATION OF ALDEBARAN 



junction. — It follows then from the first elements that the lon- 

 gitude of Porto-Rico West of Parish" 33' 26" 6, and the 

 difference of latitudes in conjunction 22' 58". — It is to be re- 

 marked that calculating from the difterent elements, there re- 

 sulted an increase in the difference of meridians between Porto- 

 Rico and Paris viz : 



From the difference between 1-330 and 1-334 for the figure of the earth. + 08 3 



From the differences of parallaxes between 57' 44'* 8, and 57' 36" 8. + 17 1 



Longitude ef Porto-Rico by the first elements 4 33 26 6 



Longitude of Porto-Rico West of Paris corrected. 4 33 52 



These results inclined me, at the moment, to believe that 

 the longitude determined by Triesnecker was nearer the truth 

 than any of die others, I immediately began a careful inves- 

 tigation, making use of the best elements astronomy has as 

 yet afforded. 



In consideration of the great influence of the parallax and 

 oblate figure of the earth, upon the longitude of Porto-Rico, 

 we may infer the great importance of repeating this kind of 

 observations, for if we can once with accuracy determine the 

 difference of meridians, we can then determine the proportion 

 of the earth's axes, with more certainty than by the Geodesical 

 method; or supposing this proportion known, the lunar pa- 

 rallax could then be determined. 



The horizontal equatorial parallax agreeably to Mayer. = 57 11 4 



_, , . r . ,.„. -> Lalande. 57 05 



These results are on the supposition ot the dinerence /g *-. qi q 



of the axes of the earth being 1-300. ^ Laplace. 56 57 3 



The parallax which I have adopted is that of Burg, who 

 deduced it from observations of a great number of solar eclip- 

 ses and occultations of stars. 



The inflection of the moon I have deduced from the same 

 observations. It will not be amiss to observe, that comparing 

 the conjunctions deduced from immersions and emersions, or 

 immersions with immersions, they give the difference of me- 

 ridians, so that the doubt which may exist as to the quantity of 

 inflection, cannot be such as to aflect the result. To determine 

 the difference of latitudes at the conjunction, I have made use 

 of die observations at Gotha and Porto-Rico. 



