AstfO)iomical Society. 



227 



Bushey Heath = 

 Epping = 



Greenwich . . = 



Dublin .. 

 Armagh. . 

 Aberdeen 



' 4%0 beginning. 

 19,0 end. 



54 ,0 end. 



11 ,5 with 25 inch acluom.") 



12 ,4 with 46 inch do. | 



13 ,4 with 5 feet equat. ) end. 

 16 ,5 with 30 inch achrom. 1 

 18,0 with 7 <eet Newt. J 



30 ,0 end. 

 10,8 end. 

 45 ,1 end. 



From these Observations Mr. Innes obtained the following results; 



The results deduced from the observations at Bushey Heath 

 marked b, b and e, and c, are obtained from the beginning of the 

 echpse, from the beginning and end conjointly, and from the end. 

 And from theae Observations Mr. Innes obtains + 9", 68 for the 

 error of the tables in longitude, and — 2",44 for the error in lati- 

 tude. The lunar tables made use of were the recent ones of M. 

 Damoiseau : and Mr. Innes has subjoined to his paper the whole 

 of the elements employed in the calculations. 



A description of an instrument called A Tangent Sextant, in- 

 tended to determine the distances of objects from an observer, when 

 their distances from each other are known, was communicated to 

 the Society by Captain John Ross, R. N. who states that it was in- 

 vented by an eminent land-surveyor, who lived to finish but two of 

 them ; and Captain Ross has since made some improvements in the 

 instrument. 



The index-mirror is placed diagonally across the bar of the index, 

 having the centre in a line with the front edge of the index ; and, 

 in observing, the telescope is so placed that the centre of the instru- 

 nient is towards the observer, and the limb directed towards the 

 objects, which are brought in apparent contact, as in other reflect- 

 ing instruments. The edge of the revolving index intersects an- 

 other fixed and grailnated radius, passing through the zero of the 

 limb ; and the figures at the point of intersection indicate the num- 



2 G 2 her 



