160 E. Loomis on Solar Spots, Magnetic Declination, ete. 
ears. The corrections which I have actually oaks are the 
following : 
The observations at Montmorency have been increased by 
one-fifteenth part. 
7 “ “ Mannheim diminished by one-fifteenth. 
é « “ Paris, 1784-88, diminished by one-fifth. 
w 6 a London, 1786-1820, diminished by one- 
nth. 
a a “ Paris, senate diminished by one-fourth. 
és se “ Gottingen, 834-40, diminished by one- 
eae ly 
The following table presents a summary of all these oe 
vations: [See page 
ese sbaarvations after r being reduced to the Pages 
standard in the manner already stated, are represented by the 
middle curve traced on the accompanying Plate. This curve 
Beas an obvious resemblance to the curve of solar spots, and in 
ong may be said to be parallel with it. The differences be- 
tween t é 
phenomena represented. Since 1884 the general correspondence 
of the two curves is remarkably close, but real differences are 
indicated in the years 1836-8, in 1842-4, and in 1864. 
is comparison seems to warrant the following propositions : 
Pe, A saeke ae evened of the magnetic declination, amoun 
at Prag about six minutes, is independent of the 
pda in the sun’s surface from year to year. 
e excess of the diurnal inequality above six minutes as 
observed at Prague, is almost exactly proportional to the amount 
of spotted surface upon the sun, and may therefore be inferred 
to be produced by this disturbance of the sun’s surface, or 
both disturbances may be pein to a common cause 
Periodical recurrence of great auroral displays.—In attempting 
e. decide whether auroral diaptaa exhibit the character of a 
a. a careful discrimination is necessary in selecting 
ta for comparison. Travelers who have wintered in some 
pau of the Arctic regions, have reported that auroral displays 
were witnessed almost eve lear night when the light of the 
sun did not interfere, even on those years when in the middle 
complete catalogue of all recor uroras, including the 142 
auroras observed at Fort Ente terprise i & 1820-1, the 148 auroras 
observed - t Bossekop i in 1838-9; the 141 auroras observed at 
