E. Loomis on Solar Spots, Magnetic Declination, etc. 165 
There are only two instances in which there is any discrep- 
ancy in the times of minima. In one of them (1744) the obser- 
vations of the solar spots are confessedly very uncertain, and in 
the other (1755) the change in the number of obse rved auroras 
rom 1755 to 1757 was only three, so that we seem authorized to 
assert that ass is an invariable coincidence in the times of 
minima of the solar spots and of auroral displays. 
The range of the maxima and minima of auroral displays is 
considerably greater than that of the solar spots, and the obser- 
vations of magnetic declination seem to indicate a similar pecu- 
liarity. There seems then to be no room for doubt that auro- 
ral displays exhibit the ten yearly period of solar spots, but the 
range of the changes on different years is subject to influences 
which may be independent of the sun. 
In order to decide whether this periodicity is exhibited in the 
higher latitudes, I have selected all those observations with 
which I am acquainted which show more scape a hundred au- 
roras ina year. The — is the ta 
Date. Place, Lat. Long. Phan Authority. 
Auroras. 
1820-1 Cumberland House, /53° 56’ wind oe 142 hac (Smith. Cont.), p. 
1820-1\Fort Enterprise, (64 28 [1 142 gd oraagg Cont.), p. ache 
1833-5 \Great Slave Lake, |62 46 : 105 Cs 
38-9) Bossekop, 69 58 | 23 34E) 143 (Vo oye ays "Scandinavie. 
1848-9/Fort Confidence, (66 54/118 49| 122 |Athabasca obs. p. 324-350 
1850-1|Moose Factory, |51 10| 8f 0O| 141 |Am. Jour ur. Sci., [2], XIV, 156. 
1850-1 Athabasca Lake, [58 43 |111 18| 109 |Am. Jour. Sci., [2 Lov 156 
1852-3|Point Barrow, 71 21/156 15| 131. |Phil. aly 1857, p. 497. 
These places are all situated within the zone of greatest au- 
roral frequency, Am. Jour., vol. xxx, p. 89. The observations 
of 1820-1 and 1833-5 were made near the time when the distur- 
bance of the sun’s surface was a minimum; while those of 
1848-9 were made when the disturbance of the sun’s surface 
was a maximum; and those of 1838-9, and 1850-1 were made 
is nearly the same as at ee last three dates. So far as 
any conclusion is warranted from so limited a number of ob- 
in a periodical change in the num mtahar of auroras; and a a 
riodicity in Europe appears to be the most distinct] 
near the parallel of 50 itada: and in New Englan har the 
parallel of 42° latitude. 
