102 
REV. J. FARQUHARSON’S EXPERIMENTS ON THE INFLUENCE 
served, however, that no disturbance took place till the fringes of the Aurora 
had gone so far south as to place the needle in their planes, or in the line of 
prolongation of the middle or most elevated streamers of the fringes, which is 
that of the dipping needle. The numerous observations formerly made by me 
this autumn, of which I have already put you in possession*, and those also 
1 Otli of October. — 11 a. m. Series of 50 oscillations : 1st in 227".75 ; 2nd in 227".5 ; 3rd in 227". 2 ; 
4th in 227 ".5 ; 5th in 227". 75 ; 6th in 227". 5. 
2 r. m. — 1st in 227". 5 ; 2nd in 227 ".5. 
4 p. m. — 1st in 227". 75 ; 2nd in 227".5. 
1 1th of October. — 65 r. m.- — V ery brilliant streamers seen, at an opening among clouds at N. W. 
reaching upwards to about 35°. Series of 50 oscillations : 1st in 227". 75 ; 2nd in 227". 5 ; 
3rd in 227".5 ; 4th in 227".75. 
7\ p. 11. — Column of very brilliant light near the horizon at the W. extremity of the prime 
vertical to the mag. mer. and arches of Aurora in the N. Series of 50 oscillations : 1st 
in 227".5 ; 2nd in 227".75 ; 3rd in 227".5 ; 4th in 227".25. 
It is evident that the differences between the averages of these series at the several periods, 
are within the limits of the probable errors of observation; so that the intensity was not sensibly 
affected by the Aurora. 
At 8 p. m. the needle on the steel point remained steady at its usual position at that hour. 
At 20 minutes past 8, needle on the steel point was still steady, with many brilliant groups of 
streamers in the N. and an arch of light below them, and another bright column at mag. W. 
On the 25ih of October the Aurora again appeared; but neither at this time could I find that 
either the intensity or direction of the needle were altered. 
17th of November. — 3 r. m. 50 oscillations: 1st in 225". 7 5 ; 2nd in 225".5 ; 3rd in 226".25 ; 
4th in 226". 
65 P. m. — A complete arch of pale nebulous light, with its vertex about 20° high at mag. mer. 
Intensity, 1st in 225". 25 ; 2nd in 225". 25. Needle on steel point steady at its usual place 
at 8 p. m. : and intensity, 1st in 225". 5 ; 2nd in 225". 5. 
A succession of arches rose one below another, and successively expired at about an elevation of 20° 
till lip. m. when the western end of one of them became unusually brilliant, and dense. Streamers. 
Intensity at this hour, 1st in 225". 5 ; 2nd in 225". 7 5 ; 3rd in 225". 5. Needle has now 3' E. var. 
from its position at 8 p. m. At 12 p. m. Intensity 1st in 225". 25 ; 2nd in 225" 25. Var. 3' E. 
On the 1 8th of November, Aurora first seen at 6 p. m. At 8 p. m. with a very brilliant arch about 20° 
high, and a few streamers, the remains of a preceding one, about 35° high. Intensity, 1st in 
225". 25 ; 2nd in 225" ; 3rd in 225' . 5 ; 4th in 225". 5. Variation at 8 p. m. 2' E. — At 9% 
v. m. ; Intensity 1st in 225". 25 ; 2nd in 225". — At 10 p. m. Var. 4' E. — At II5, Var. 3' 20" E. 
19th of November. — At 2 p. m. ; Intensity observed, 1st in 225" ; 2nd in 225" ; 3rd in 225" ; 4th 
in 225". 25. 
At 8 p. m. Aurora first seen. A pale light through many clouds about 15° high. Variation not 
altered. Intensity, 1st in 225" ; 2nd in 225". 25. 
The variations at ] 1 and 12 r. m. of the 17th of November, and at 8, 10, and 11^ p. m. of the 
1 8th of November, were within the limits of the irregularities of the diurnal variation.] 
