. 
Miscellaneous Intelligence. 141 
i ¥ 
that for the amount of magnetic disturbance, which accordance is suffi- 
ciently close to permit us to complete it, by assuming that the number 
of aurore is a principal minimum in summer. 
long ago obtained by Mairan; this statement, made chi au- 
thority of Kemtz and Hansteen, is not quite accurate. It is true that 
Mairan’s numbers give a rough indication o law, as wil 
below 
vations (229) of which he could find a record for upwards of 1,000 years, 
it will be evident, that the conclusion that a greater number of aurore 
occurred at both equinoxes than at the winter solstice would have been ~ 
hasty ; this conclusion, however, is not made by Mairan, and, though he 
has combined the numbers of aurore in a great variety of ways, he has 
made no combination exhibiting this fact. It did not enter into the ne- 
| ; Jan. | Feb. |Mar. | Apr.|May. [June.|July. Aug. Sept. | Oct. Nov. | Dee Sum. 
|Mairan, . | 21| 27] 201 iol. 1) 5] 9 84] 50} 26] 15) 220 
Kemtz, . | 229) 307| 440) 319| 184, 65| 87) 217, 405) 497) 285] 225/3263 
Hansteen, . | 29} 31|47| 34) 2 0) 0} 17| 35] 383] 34) 28) 285 
ss A. Broun, | 22} 26] 28| 16) 6 0| 0 7) 16 20 93| 11| 184 
otek oa 280) 364| 515| 362 192 65 87 241) 456) 559, 842) 259/8792 
HE : aay ee be Te 
Mairan’s numbers are ‘probably included by Kemtz; a few of the 
aurore, included in M. Hansteen’s list, are identical with those in my 
ot ea 
his i 
visibility can be considered. ‘The French Commission du Nord, during 
heir stay in Lapland, found aurore existing, or probably existing, almost 
every night. In such places variation of frequency there is none, and 
variation of intensity alone remains for investigation. It is obvious, 
i 
