158 LE. Loomis on Solar Spots, Magnetic Declination, ete. 
actual amount of spotted surface for each month, and the 
amount indicated by the normal ten yearly curve. These dif. 
ascot are mainly the effect of causes whose period is less than 
10 now we arrange these numbers in appropriate col- 
umns eanlaied by the times of gk St of Venus and the 
earth, and take the averages of the different columns, we shall 
find that the results follow (in the main) an obvious law, as 
will be seen in the following table, showing the 
Spotted surface of the sun dependent upon the conjunctions of Venus and the Earth. 
1854 Fob. = Inf. conj. P cs tag Belpre : re i aga sel aa 4 
Dec. up. conj. —198|— 34)/— 47/-+ 10|—147|—107 
1855 Sept. 30. Inf. conj.| __ + 6|— 73/4+311|— 75/+369}+114|— 50|— 93 
1856 st 20. Sup. conj.|__ g3|__ agi—_ g0|— 38|— 35/4 35/— 2/4 40 0 
1857 May 9. Inf. conj ee Ol+ 9+ 20/4138/— 30|/— 48/— 55 
1858 Feb. 28 Sup. conj./___ 5/___ 30/165; +._ 16|-+240|— 83/+ 20 —160| +280 
‘Dee. Cs Inf. + 45|—177|— 90|+419|+ 62|+494|-364/—214/— 58 
9 Sep. 27. Sup. conj.| 167) + 183] +443] +488] +285 +960|—235/— 65|—670 
1860 July 18. Inf. conj. 115, —460| + 625, + 640] + 900, + 750/-+135 —300|—670 
—305|—900|—600|—180| +72 35|— 100 
cs | 80|+720\+-235|—565|— 25\+ 
- 87-177) + 24 +163] +231 +317 —102 —108|—141 
The curve of the accompanying —Plonths Before. ee 
Bee Ss. 
figure represents these average +300 ' 
a 
results, and shows that the prin- ie 
cipal part of these differences may i ae | 
be represented by a simple curve , f 2 
whose period is 9°7 months ; being / . | 
the period between the successive ‘ 2 Pa 
al a ae of Venus and the sun 3 
the heliocentric conjunctions -™ 7] 3 Dy 
i ePpaens of Venus and the EN T 
eart 
The Ecene facts are thought to warrant the following 
propositions 
1. The mean interval between the successive maxima of the 
seg spots is almost exactly ten years. 
The value of the maximum of the solar spots is variable, 
ae being generally two or three successive maxima o 
sual magnitude, followed be we or three maxima which are 
ee — the average magn 
e normal ten- ee curve, are a 
mined by the heliocentric conjunctions and ogee of Ve 
nus and the eart a 
. The fluctuations in the period of the solar spots from 7 to 
13 ‘years, and the great fluctuations in thes amount of the suc- 
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