SURVEY OF THE BRITISH ISLES FOR THE EPOCH JANUARY I, I88G. 
93 
The results at Kew and Greenwich show that the secular variation varies so much 
from year to year that it is practically impossible to draw any conclusions from so 
short a period as 2 or 3 years, and our own observations on Scotland show that if to 
this difficulty, that due to a slig’ht variation in the position in a disturbed district is 
added, the results are still less trustworthy. At the time when the reductions were 
made the Greenwich results for 1886 and the Stonyhurst results for 1887 had not 
been published. We therefore took the mean of the values for Stonyhurst 1883-1886, 
Kew 1883-87, and Greenwich 1883-1885, or + 0'0022 the annual increase for 
England. This value is in fair accord with M. jVJoureaux’s results. In Scotland we 
took the number given by the comparison of our own and Welsh’s observations, viz., 
+ O’OOIB, and for Ireland -f 0'0020. 
Results of the Observations. 
Having- thus described the observations and the methods of correction and reduction 
to epoch, we now proceed to give a more detailed account of the results at each 
station. In doing this we have attempted to distinguish between facts which it is 
necessary to give for the information of most of those who may read our paper, and 
details which ought to be preserved, but which will nevertheless only be of interest 
to observers who may for any cause wish to undertake a detailed examination of our 
results. We have therefore decided to publish in this paper only a description of 
each station, the hours at which the observations were taken, the results corrected for 
diurnal variation and disturbance, and the mean reduced to epoch. As Magnetic 
Observatories and provincial Colleges are now rapidly multiplying, it is not too much 
to hope that special studies of the districts in their immediate neighbourhood may 
from time to time be made by those connected with such institutions. It is, therefore, 
we think, important that the descriptions of the sta.tions should be readily accessible. 
In adding to these only the times at which the observations ’were taken, and the 
actual and reduced results, we are publishing far less than has been usual. Thus, in 
the case of the Rev. S. J. Perry’s survey of the east of France, he gave for the Force 
observations the date, hour, and temperature for both vibrations and deflections, the 
time of one vibration, log mX., the distances of the magnets in the deflection 
experiment, the observed deflections, and log m/X. M. Moureaux has not given 
quite so many details of the Force observations, but in the case of the Declination he 
gives the individual readings for the determination of the geographical meridian, &c., 
so that the description of his work at each station occupies about two quarto pages. 
For our own part we have no fault to find with the publication of these details ; on 
the contrary, we have found them to be useful; but the large number of stations 
included in our survey ‘svould, we fear, make this paper inordinately long if we 
adopted a similar plan. We therefore purpose to place in the hands of the Royal 
Society bound copies of the details of the observations and calculations, and also of 
