between the Observatories of Armagh and Dublin. 



139 



It will be observed that both clocks were accelerated at the 15""; this was 

 chiefly caused by a fall of the barometer of three-fourths of an inch (Memoirs 

 Ast. Soc, vol. V. p. 125). The mercurial pendulum of my clock is accelerated 

 0'. 37 by a fall of one inch ; the coefficient for the gridiron pendulum which 

 belongs to the Dublin clock is probably greater, but as the effisct is only dif- 

 ferential, it seemed unnecessary to allow for it. 



The differences of longitude given by the signals are as follows : 



t2 



