No. XXII. 

 CALCULATION 



Of the Longitude of Tale-College, from the Solar EcUpfe 



of September 1 7//', 1811. 



By JEREMIAH DAY and JAMES L. KINGSLEY, 



Professors in Yale-College. 



IT is important, that the Latitude and Longitude of 

 places, especially of thofe in which aftrononiical obfer- 

 vations are to be made, fhould be fettled, with as much 

 accuracy, as the nature of the cafe will admit. 



The Latitude is eafily obtained, from the meridian 

 altitudes of the fun, and the fixed liars. But fome 

 more complicated procefs is neceffary, for determin- 

 ing the Longitude. Moft of the methods in ufe, 

 for this purpofe, depend on the motion of the moon 

 in her orbit. Several of them, however, cannot 

 be relied on, to give the longitude, with any great de- 

 gree of accuracy That founded on the obfervation of 

 folar eclipfes, has an advantage in this refpect, over moft 

 of the others. As we had leen no circumftantial ac- 

 count of any attempt, to afcertain the longitude of Yale- 

 College ; we made preparations, to avail ourfelves ©f 

 the opportunity furnifhed, by the eclipfe of the fun, 

 of Sept. 17th 1811. The going of the clock, from 

 which the time was to be taken, was carefully attended 

 to, for feveral months preceding. Its rate was found, 

 by obferving the paffage of the fun and fixed ftars, acrofs 

 the meridian. A tranfit inftrument, with a telefcope 

 of about twenty inches focus, had been fixed, under 

 the cupola of the Lyceum, nearly two years before. 

 Care had been taken, during this period, by repeated 

 obfervations of the pole fi:ar, to obtain an accurate ad- 

 juftm.ent of the telefcope in the plane of the meridian. 



