Ckase.] 518 [Sept. 20, 
Tn each curve there is a tendency to monthly maxima, the tendency be- 
ing least evident in the summer months. 
The principal minimum in each curve is in June. 
There are nine marked maxima in each curve, of which those in the 
months of January, February, March, April, September, October and 
November, are the most nearly accordant. These maxima are as follows : 
A, Jan. 13, Feb. 22. Mar. 16., Apr. 13.°.<:.. July 7)... . Sept.:25. 
Oct. 20. Nov. 14. Dec. 14. ‘ 
M. Jan. 8. Feb. 7. Mar. 9. Apr. 8 May 18. .... Aug. 6. Sept. 10. 
Oct. 20. Noy. 14.7.0 .. 
Two of the maxima are synchronous in the two curves ; three occur in 
the auroral ordinate which follows the meteoric ordinate ; two occur in 
the third subsequent ordinate, one of the two being midway between a 
precedent and subsequent meteoric ordinate. The accordances and the 
discrepancies may perhaps be explained by the hypothesis of lunar per- 
turbations. 
The daily curves present a similar accordance in the number of 
maxima and minima, but in consequence of the frequent uncertainty 
whether the auroral or the meteoric should be regarded as the precedent 
influence, they do not seem to furnish any additional data for satisfactory 
conclusions. 
By variously grouping the auroral observations on each side of the 
days that have been designated by Wolfe and Kirkwood as rich in meteoric 
displays, or on each side of the middle days of meteoric periods, a variety 
of curves may be formed, of which the three following sets of ordinates 
furnish examples : 
Days. —7 —6 —5 —4 —3 —2 —1 0 41424844 +5 +46 +7 
a 100 99 100 102 104 106 106 104 103 105 107 108 106 101 99 
B 99 99 97 97 97 99 101 101 100 101 102 102 104 104 102 
7 103 102 101 98 97 98 98 99 101 101 101 103 105 101 98 
These curves indicate a connection of meteoric displays with increasing 
auroral displays, together with a slight subordinate tendency to auroral 
maxima within one day of a meteoric display. 
Although the wthereal disturbance, which is manifested by the auroras, 
appears to follow, more often than it precedes, meteoric falls, it seems 
probable that both phenomena are often dependent upon lunar pertur- 
bations or other extraneous causes. In such cases, the auroras may be- 
come visible before the meteors have reached the carth’s atmosphere, and 
been made incandescent by friction. 
STELLAR AND PLANETARY CORRELATIONS. 
By Pror. Purny EARLE CHase. 
(Lead before the American Philosophical Society, Sept. 20, 1872.) 
Merecury’s mean distance may be grouped with the mean distances of 
other primary planets, so as to form the two following series :* 
*In each table, C denotes the logarithm of the computed value; O, the logarithm of the ob- 
served value; Lk, the percentage of error in the computed value; 4, the limit of retardation by 
solar rotation aud of possible solar atmosphere; M, modulus of light. The fundamental unit 
is the suus’s radius, The origin of the co-ordinates is taken at the intersection of the axis and 
the directrix, ‘ 
