418 



Astronomical and Nautical Collections, 



iv. Principal Lunar Occultations of the Fixed Stars in the 

 months of February and Marchy 1829, calculated for the Royal 

 Observatory at Greenwich. By Thomas Henderson, Esq, 



The calculations having been performed in an approximate 

 manner, observers are advised to be prepared two or three minutes 

 before the times above stated. The fifth and seventh columns show 

 the point of the Moon's Limb where the immersion and emersion 

 will take place, reckoning from the vertex or highest point, the 

 letters L, and R. signifying towards the observer s left and right 

 hand. 



[To be continued,] 



V. Computation of Longitudes on a Spheroid. 



A geodetical line may be considered as belonging, through- 

 out each element of its length, to the conical surface which 

 is a tangent to the curved surface on which it is described ; 

 and the surface of every cone being capable of being unrolled 

 on a plane, without any alteration of its elementary form, 

 the corresponding elements of the curve must form straight 

 lines by this developement. 



