N griBT" BATH in KINC Tin: nvn.M. M AI> 1891 T<> iMt 385 



difference between the greatest and least mean hourly values) and the numerical sum of 

 the differences of the 24 hourly values from their arithmetic mean. All pronounced 

 maxima and minima values are printed in heavy type. In most months two maxima 

 and two minima are distinctly shown by each element, but sometimes only one pair 

 ap]jears. The phenomena are so similar to those at Kew, that a brief discussion 

 will suffice. 



Declination. 



7. From October to March there are in Table V., as at Kew, two pronounced maxima 

 and minima, and in one or two other months there is a suspicion of more than one 

 maximum and minimum. In the mean diurnal inequality for the year there is but a 

 very short interval between the night maximum and minimum. The time at which 

 the needle reaches its extreme westerly position is nearly constant throughout the 

 year. The extreme easterly position is assumed in December about 10 P.M., but in 

 all the other months of the year about 8 to 9 A.M. The hours of maximum and 

 minimum look later than at Kew, but that is mainly, if not wholly, due to the 

 difference in local time. 



In addition to the December minimum, prominent in all the elements, the ranges 

 and the sum of the differences show, as at Kew, a second inconspicuous minimum at 

 midsummer. The interval between the two apparent maxima in the ranges is, as at 

 Kew, longer than that tatween the two maxima in the sum of the differences, the 

 latter appearing at l>oth stations in June and August. 



The monthly ranges and sums of the differences appear, on the whole, a trifle 

 smaller than at Kew. This is really attributable to the fact that the mean sun-8]>ot 

 frequency for the Falmouth period 1891 to 1902 was slightly less than that for the 

 Kew period 1890 to 1900. During the common period 1892 to 1895, in the mean 

 diurnal inequality for the year, the Falmouth range was the greater by /- 10, whilst 

 the Kew sum of the differences was the greater by 0''57. As these differences 

 represent only about 1 per cent, of the quantities themselves, the only safe conclusion 

 is that the amplitudes of the diurnal inequality of declination at Kew and Falmouth 

 are exceedingly nearly equal. 



Horizontal Force. 



8. Two maxima and minima are shown from October to April, somewhat 

 doubtfully in April ; in the remaining five months there is at least a retardation in 

 the fall of H about 3 or 4 A.M. The mean inequality for the year shows two 

 maxima and minima, but the morning maximum and minimum are poorly defined. 

 The least value of the day occurs about 10 or 11 A.M., earlier in summer than in 

 winter. From November to February the largest value is met with at 6 or 7 A.M., 

 but throughout the equinoctial and summer months the absolute maximum occurs 



VOL. eciv. A. 3 D 



