GRAPHS OX "QUIET" DAYS 1>U;IN<; Till: TWI.l.Vi: VK.MW 1891 TO 1902. 375 



S,; a I <ir 



2. As in (A), use will frequently be made of the letters D, H, N and W to denote 

 respectively Declination, Horizontal Force, Northerly Component and Westerly 

 Component of Force. Only two of these elements, of course, are independent, and 

 they are connected hy the relation 



N/cos D = W/sin D = H. 



The system of absolute observations at Falmouth and the method of standardizing 

 the curves are the same as at Kew (see (A), 4). 



Table I. gives the mean yearly values of D and H as deducible from the diurnal 

 inequality data in the annual Falmouth Reports, with the values of W and N 

 calculated therefrom, and the values thence deduced for the annual changes. The 



TABLE I. Secular Change. 



absolute values of H, W and N are expressed in C.G.S. measure ; the annual changes 

 have for unit ly = 1 x 10~ 5 C.G.S. In the case of D and H the differences from the 

 corresponding annual changes at Kew are given in brackets, the + sign indicating 

 that the Falmouth change was numerically the larger. 



The total decrease of declination between 1891 and 1900 at Falmouth was 

 absolutely identical with that at Kew ; even in individual years the results at the 

 two stations show a very fair agreement, the mean difference irrespective of sign 

 being only 0''5. As at Kew, there is subsequent to 1895 a marked slackening in the 



