170 Professor Airy on the Longitude, Sfc. 



For the reasons stated in the commencement of this paper, 

 it is clear that the longitude which must be adopted for the 

 purposes of the Observatory, is that which has been determined 

 by the comparison of the clocks. Until some more accurate de- 

 termination is made, I shall therefore consider the longitude of 

 the Cambridge Observatory as 23',54 East oi the Greenwich 

 Observatory. 



The importance of the general question discussed in this paper 

 is perhaps sufficient to warrant me in laying before the Society 

 an attempt, however imperfect, to establish a fact which has some 

 bearing upon that question. And to the members of this Society 

 the determination is not altogether wanting in local interest. 

 But there is another reason which has operated still more strongly 

 in producing this di.ssertation on the longitude of the Cambridge 

 Observatory. It is the wish and the hope of the present director 

 of that establishment, that it may rise in time to an importance 

 in the Astronomical world, which will make the exact determi- 

 nation of its geographical situation, and of the position of its 

 meridian-plane, not only desirable, but necessary. A determi- 

 nation like that now presented, if it be judged to be accurate, 

 will then acquire a value to which at jiresent it can make no 

 pretensions. 



G. B. AIRY. 



Observatory, Cambridoe, 



Nov. 20, 1828. . 



