866 



Proceedings of the Royal Irish Academy. 



The probable error of one complete obseryation is ± '15. 



The sum of the squares {nn) = 3-537. 



The sum of the squares (w) - 2'935. 



The result of the observations is therefore to indicate a parallax of 

 about one-third of a second for Gr. 1618. Though the probable error 

 of the result is only 0"-05, yet there were certain features which 

 seemed to me to require further examination. The signs of the resi- 

 duals look as if some systematic irregularity had affected the measures. 

 The large value of the unknown k seems also somewhat improbable. 

 The substitution of the values for the unknowns only abates the sum of 

 the squares of the absolute terms from 3-5373 to 2-935. I therefore de- 

 cided to commence another series of observations, in the hope that the 

 experience already obtained would ensure a better result. 



Geoombeedge 1618, II. 

 Corrected Distances of+ 50°, 1724/rom Gr. 1618. 



Date. 



Distance. 



Date. 



Distance. 



Date. 



Distance. 



1879. 





1880. 





188C 



. 





Aug. 14, 



197"-187 



Mar. 



12, 



196"-473 



April 



25, 



196"'629 



„ 23, 



196 -846 





15, 



196 -398 



,, 



27, 



196 -589 



Oct. 28, 



197 -184 





18, 



196 -170 



May 



6, 



196 -432 



Nov. 1, 



196 -935 





19, 



196 -577 



5, 



7, 



196 -255 



11, 



197 -079 





19, 



196 -524 



,, 



8, 



196 -317 



„ 13, 



196 ^841 



,, 



20, 



196 -862 



,> 



13, 



196 -466 



„ 30, 



197 -228 



,, 



21, 



196 -557 



)' 



15, 



196 -319 



Dec. 4, 



197 -056 



„ 



21, 



196 -489 



,, 



16, 



196 -577 



10, 



197 -177 



„ 



22, 



196 -545 



July 



15, 



196 -191 



„ 17, 



196 -970 



,, 



22, 



196 -626 



„ 



16, 



195 -807 



„ 18, 



1880. 



Jan. 9, 



196 -817 

 196 -985 



April 



31, 

 6, 



196 -924 

 196 -452 



,, 



20, 

 21, 



196 -009 

 195 -748 



„ 21, 



196 -961 



„ 



8, 



196 -583 



,, 



21, 



195 -852 



Feb. 4, 



197 -077 



„ 



22, 



196 -517 



„ 



29, 



195 -757 



5, 



196 -985 



J, 



24, 



196 -ssa 









