The Aurora Borealis. 



401 



As avery careful watch was maintained over the smallest irregularities of motion in the declination, bifilar, and 

 balance magnets, throughout thewhole of the yearl84-l, it is believed that the preceding Table contains a near ap- 

 proximation to the absolute ranges of the three magnetic elements for each civil observation-day of the year 1844. 



TABLE LXI. — List of Aurorse seen at Makerstoun in the year 1844. 



Several of the aurorge noted faint were marked as somewhat uncertain, on account of remaining twilio-ht 

 or clouds ; there can be little doubt, however, that in every case they were real aurorje, as they wei'e accompa- 

 nied by more or less marked magnetic disturbances. 



The Aurora Borealls. 



The previous Table contains a list of all the aurorse observed at Makerstoun in the year 1844. The 

 number is too small to expect from it alone any general results ; but as it is believed that a discussion of the 

 number seen gives nearly the same results as Avill be obtained from more extensive series, the conclusions are 

 stated here. 



The number of aurorse boreales seen at Makerstoun in 1844 was 26. The numbers seen in each month 

 were as follow : — 



The number is zero in June and July ; the shortness of the night and brightness of the twilight would of 

 themselves diminish the number observed in these months ; for the opposite reason we should expect a greater 

 number about the winter solstice : this, however, is not the case, — the gi-eatest number occurs in the months 

 of March and November. Between the summer solstices of 1843 and 1848, 5 years, 85 aurorae were seen at 

 Makerstoun, which, considering the year in 4 quarters each of which has a solstice or equinox at its centre, 

 occurred as follow : — 



Vernal equinox, 32 ; Summer solstice, 6 ; Autumnal equinox, 23 ; Winter solstice, 24. 



Although the quarter at the winter solstice is so much more favourable for seeing aurorse, on account of 

 the greater length of the night, the average number at the equinoxes is greatest. 



This result was long ago obtained by Mairan in his Traite de I'Aurore Boreale, and has lately been 

 obtained by M. Hansteen from observations of nearly 300 aurorse seen in the years 1837-1846 at 

 Christiania.* It is, of course, partly accidental, that there is an approximation to the law distinctly evident in 

 the single year's observations for 1844 : the fact is stated chiefly in order to point out its connection with a 

 result of the previous discussions. The law of the frequency of aurorte is the same as that of the intensity 



* Memoires de I'Academie Royale de Belgique, tome xx. Kamtz, also, in his Complete Course of Meteorology (translation by 

 Walker, p. 458), gives a Table, comprehending 3253 aurorse. The following are the numbers by Kamtz and Hansteen : 



Jan. Feb. Tilarch. April. 



Kamtz 229 307 440 312 



Hansteen,... 29 31 47 34 



MAG. AND MET. OBS. 1844. 



May. 

 184 



June. 



65 







July. 



87 

 



Ang. 



217 

 17 



Sept. 



405 



35 



Oct. 



497 



33 



Not. 



285 



34 



Dec. 



225 



23 



Si 



