OF THE SUN, JVNE 16, 1806". 259 



From the same to the saint. 



Read September 19th, 1806. 



Lancaster, August 16th, 1806. 



Three days ago, I received a letter from my friend, Mr. 

 Dunbar, at Natchez, containing his observations on the solar 

 eclipse of the 15th of June last: they are as below. 



•-Beginning J ^ | K ? * IT £ A . M . Apparent Ume ,, 



In deducing the latitude and longitude of the moon, from 

 the above observations, I have diminished the sum of the semi- 

 diameters of the sun, and moon 5", for the effect of irradiation 

 and inflexion: — the altitude of the pole 13', and the horizon- 

 tal parallax of the moon 4" on account of the spheroidal figure 

 of the earth. 



bin 



B >' 1 the enf nl " S } the ^junction was at [ *$ \ 5 . g" j Mean. 10 15 20 5 

 The conjunction at Philadelphia by your observations. 



I- 



Difference of meridians. . . . 



Whilst residing at Natchez, some years ago, I settled the difference 

 of meridians between that place and Philadelphia, from my obser- 

 vations at 16" 15' 46 "• 



difference only 



Let us now take the longitude of Philadelphia, (as long settled) ? 

 for a given point ..... $ 



Add the difference of meridians between Philadelphia and Natchez. 



Longitude of Natchez. ... 



Conjunction at Philadelphia by your observations. . 



Conjunction at Lancaster. . . . . . . 



Difference of meridians. .... . 



Add longitude of Philadelphia. .... 



Longitude of Lancaster. ..... 



This longitude exceeds that drawn from the measure of the turnpike? 17 



road, and some of my former observations. . . $ 



The difference of the meridians as above stated, agree so 

 nearly with former determinations, that there can remain but 

 little doubt, that the difference in longitude, between the pla- 

 ces above mentioned, and Greenwich, as drawn from the late 

 eclipse of the sun, and as heretofore settled, arises principally 



* Sec Philosophical Transactions, Vol IV. page 451. 



