MAGNETIC FORCE IN IRELAND. 



185 



TABLE I. (Continued.} 



The computed results of the preceding observations are given in 

 Table II. The first and second columns contain the place and the 

 date of the observations ; the third the designation of the needle em- 

 ployed ; in the fourth column is given the mean time of 100 vibra- 

 tions, corrected for temperature and for the rate of the chronometer ; 

 and the fifth and sixth columns contain the computed values of the 

 horizontal intensity the numbers in the fifth column being the 

 ratios of the horizontal intensity at the place of observation to that 

 at the station of the observer, and those in the sixth being the 

 ratios of the same force to that at London, to which place all the 

 observations are ultimately referred. 



If T denote the reduced time of 100 vibrations at any place, 

 and T' that at the station with which it is immediately compared, 



