532 
^IR. A. W. RUCKER AND DR. T. E. THORPE ON A MAGNETIC 
The agreement between these assumed rates of secular change and observation is 
illustrated in the next table. 
We have distributed the results obtained from the central stations (indicated by 
C.S. L, &c.), from the groups of repeat stations, and from Kew and Stonyhurst into 
eiglit secondary groups, according to their geographical positions. In two cases a 
group consists of only one central station. The observed secular changes taken from 
Tables X.-XIfl. are compared with the calculated values deduced from Table XIY. 
It will be seen that the means of the observed and calculated results are in fair 
accord in each group, and that the means of the means are practically identical. 
Hence the secular changes deduced from Table XIV. do, on the average, a.gree 
with experiment, and this agreement is not due to serious errors in different parts of 
the couiil.ry neutralizing each other, as the differences between the mean results of 
calculation and experiment are small in all districts. 
