ay 
May 28, 1885] 
NATURE 
89 
brightness of the northern nights. The perspicuity with which 
the yearly course of the period is drawn’in the four representa- 
tions of Fig. 1 may even be called surprising, considering the 
material of observation only embraces three years. 
Fig. |. 
Kistrand 
JULY AUG. SEPT. OCT. NOV. DEG. JAN. FEB. MARCH APRIL MAY JUNE JULY 
TABLE III.—Léding:n 
Month 1881 to 1882 1882 to 1883 1883 to 1884 Total 
July 3 oT 3 Io 
August 6 3 I 10 
September... 9 3 3 14 
October 8 II I 20 
November... 8 14 4 26 
December... 2 5 fo) 7 
January 5 4 fo) 9 
February 10 10 3 2 
March... 9 9 6 2 
April 10 4 3 17 
May Gj 3 2 12 
June 2 6 fo) 8 
WG Eos 92) oe 75 26 180 
TABLE IV.—Bevgen 
Month 1882 to 1882 1882 to 1833 1883 to 1884 Total 
July 2 mes I cee 3 Bs 6 
August fo) 3 2 5 
September... 5 I I 7 
October 5 3 4 12 
November... 6 ce 10 3 19 
December... 6 6 I 13 
January 3 I 2 6 
February 3 9 fe) 12 
March... 10 4 4 18 
April ... 9 3 I 13 
May 4 2 fo) 6 
June 3 I fo) 4 
WMearm <7. 56 a 44 no 21 121 
Tables I. to IV. will show the great frequency of these tele- 
graphic perturbations in Norway compared with those of all 
other countries in Europe. In the totals of the years a constant 
decrease for all four stations is visible which decidedly coincides 
with the diminishing appearance of the aurora during recent 
years in this country. After some years it will probably be 
seen how the telegraphic perturbations have the 11-year period 
in common with the aurora. 
In order to determine the daily period, I have investigated 
how often during the three years in every hour from 7 a.m. till 
midnight perturbations have been observed (excluding those 
caused by thunderstorms). Table V. shows the result :— 
TABLE V. 
7 8 9 10 IL 12 
Kiustrand) 7 yee odometer Uaieere LOO) ms.) at 137 
ronc hy emission Oey OTN en SON en mnsO 
(odin gen\ ereep a Uleesmens Omen 30 lnc 4 Onin eee 
Bergen ... san. 2} tan 9 Beh ee lato Psst oo 8232) 
I 2 3 4 5 6 
Keistrand ~ \pcamtoowe: SOOM en TOO wert Gurr Lye. LOI 
Mrondhjem’ 7) fSrees | Olas | 75s) OS) X20. 125 
Lidingen” =), “36"e. 4043 57 ee 70) =. 80) 
IBergeni ee en e2ymees (4 Queens) creat 4 Onna 2a, 
8 9 10 Il 12 
Kistrand CAAT cae Oe) gua sh) cee = eco ce 
Mrondhjem| <0) 23/7) 20S Ons RG Our ety) 7am OOM me On 
Todingen’ 2-490) 5) G64 sse5 LOON:=-) 70) ex= OLS mms 4 
isexsiconsters iy Ole Woe Goes Ci as GS) 
Fig. 2 gives these numbers in graphic representation. It will 
Fig.2, 
/s 
/ 
/Kistrand 
ie Trondhjem x 
at : 
\ 
y : 
/ Lodingen \ 7 
/ 
“~” Bergen 
be seen that the telegraphic perturbations show a very prominent 
maximum in the evening, 8 till 9 o’clock. Intimations of a 
trifling maximum (with the exception of Bergen) to till 11 a.m., 
and a succeeding minimum I to 2 p.m. are also visible. 
Other occupation taking up my time at present a more ex- 
tensive and detailed investigation must be postponed. 
Christiania SopHus TROMHOLT 
A NOTE RELATING TO THE HISTORY OF 
THE AUVKORA BOREALIS 
P\ MONG northern authors none has given the writers on the 
Aurora Borealis more to trouble than Peder Clausson 
Friis, 1566-1614, Minister at Undal, near the town of Mandal, 
in Southern Norway. This, for his time, very productive 
