MAGNETIC FORCE IN IRELAND. 



203 



inferred from one only, the weights may be assumed as follow : 

 A = 3, 5 = 1, (7=1. 



Substituting these values, therefore, in the formulas alluded to, we 

 find 



x = a + B x = 1-0210, y = b + $y = 1-0251. 



The numbers in the fifth column of the table are deduced from 

 those in the fourth, by multiplying by one or other of these 

 numbers, according as the force at the station in question has been 

 compared in the first instance with that at Dublin, or with that at 

 Limerick. 



TABLE VI. 

 Intensity. Needle L (4). 



Evident local distm-bance at these two stations. The district about Carlingford 

 is intersected with trap dykes; Coleraino lies within the basaltic field of the North 

 of Ireland. 



