Magnetic Declination. 



3a7 



TABLE V. — Hourly Means of "Westerly Declination for each Month in 1844. 



Table V. is intended chiefly as a key for comparing the hourly observations. 



The true mean time at Makerstoun is 10™ in advance of the numbers given in the second column of Table V. 



Diurnal Variation of Westerly Declination. — The mean result for the year 1844, may be stated as follows: 

 — The north end of the declination magnet was farthest west at 40™ past Noon, Makerstoun mean time; it 

 then moved towards the east till about 10'' 0™ p.m., having moved through about 8'; from lO"" p.m. 

 till 2^ 40™ A.M. it moved 1' towards the west, returning afterwards till Q^ 10™ a.m., 0'-3 towards the east 

 again ; from 7*" a.m. till C" 40™ p.m. it moved through 7' to its farthest westerly position. The mean diurnal 

 variation for the year, therefore, consisted of two maxima and two minima of westerly declination, the minima 

 differing only 0'-7 from each other. In these, as in the folloviing cases, the approximate epochs of maxima 

 and minima are obtained from the projected values by gi-apliic interpolation. 



The principal maximum occurred at the following times in the difterent months of 1844 : — 



.Tan. 

 O'^IO"' 



Feb. 

 QhlOm 



March. 

 li'lO™ 



April. 

 O*" 30™ 



May. 

 IhlQm 



June. 



Ihjo™ 



July. 

 PIO™ 



Aug. 

 0" 30™ 



Sept. 

 Ohio™ 



Oct. 

 0h40n 



Nov. 

 Ohio™ 



Dec. 

 0''20™ 



The principal maximum, therefore, occurred nearer noon in Winter than in Summer, and nearer noon in 

 August and September than in March and April (this is evident whether mean or apparent time be employed). 



The principal minimum occurred between b^ and 7"" a.m. in the months of May, June, July, and August, 

 and before midnight in the other months of the year. The following are the approximate times for each 

 month. 



IQh 



in. Feb. 



P.M. 10'' 



March. 



10"? 



April. 

 ll"? P.M. 



May. 

 6" 30™ A.M. 



June. 



6h lo™ 



July. 

 S^ lOn 



Aug. 

 6'' 1 A.M. 



Sept. 



8'' p.m 



Oct. 



Nov. 



gh? 



Dec. 

 10" ? P.M. 



On account of considerable irregularities occurring in some months near the epoch of principal minimum, 

 the times, in consequence, ai'e frequently very rough approximations. 



MAG. AND MET. OBS. 1844. 4 Q 



