1871.] 1 81 [Chase. 
that the question is an open one. And if he will compare my previous 
tabulations with those which accompany the present paper, he may, per- 
haps, find any lingering skepticism shaken, however prejudiced or invet- 
erate it may be. 
For convenience of comparison, I represent, in each instance, the mean 
rainfall for the entire period under consideration by 100, and any devia- 
tion from the mean, whether of excess or deficiency, is denoted by the 
addition or subtraction of a corresponding percentage. The smoothing 
by successive means is uniform in all the tables. I invite special atten- 
tion to the columns of lunar rainfall at Lisbon, in each of the first two 
tables, representing two different sets of three independent periods, averag- 
ing 64 months, a cycle which T have hitherto supposed too short to yield 
any satisfactory results. If there is no causal nexus, it is difficult to imagine 
any possible reason for the striking similarity between the ordinates for 
the different cycles, a similarity which I think quite as striking as that 
between the solar curves at the same station for independent periods of 
similar duration. If the lunar disturbances are considered as merely 
tidal, while the solar are partly tidal, but principally thermal, their rela- 
tive magnitudes suggest interesting comparisons between centrifugal and 
centripetal forces, analogous to those which I have hitherto had the 
honor of presenting to the Society. 
The resemblance between the independent curves in Table III. is not 
very marked ; but the yearly mean is curiously like the yearly averages of 
the lunar monthly ordinates in Tables I. and IL., if we construct the 
curves so as to compare the ordinate of Jupiter’s opposition, No. 16, with 
the ordinate of lunar conjunction, No. 1, and vice versd. 
Sn fh ane pasuir te 
TABLE IY. 
Comparative Daily and Yearly Rainfalls. 
Bx PHILADELPHIA. GREENWICH. 
be ee CR ee ee i See ee rs ee a 
a of Averge Ave’ge 
OR June. Dec. April Oct. Daily. Annwl]. Jan. July. April. Oct. 
oe 123 92 “120 eee 
2 111 78 130 
3 92 72 127 
As 17 gs 118 
Bi. 69 7 103 
6.. a 73 86 
40% 79 8 77 
Bes 
56 87 64 
55 85 67 
66 90 uh 
92 100 82 
131 116 94 
172 136 11 
\ 
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