Re 
July 19, 1872.) 523 rohade. 
CYCLICAL RAINFALL AT SAN FRANCISCO. 
By Purny Ear_e CuAse, PrRoressor oF Puysics In HavERFORD 
COLLEGE. 
(Read before the American Philosophical Society, July 19th and October 
18th, 1872.) 
Although I know of no good reason for admitting that the question, 
whether the moon exerts an influence upon the weather, is still an open 
one, there is, undoubtedly, considerable uncertainty as to the value of any 
predictions that may be based upon such influence, liable, as it is, to local, 
accidental and variable disturbances, partly of a known and partly of an 
unknown character. On this account, I think it desirable to collect and 
discuss all accessible records of observations extending over a period of 
ten or more years, especially in the neighborhood of sea-coasts and large 
bodies of water, in order to find how the lunar weather-curves are modified. 
by the forms of continental relief, the average hygrometric condition of 
the air, the changes of wind, and other obvious or more obscure sources 
of perturbation. I am willing to devote all the time I can spare from 
TABLE I. 
Different and non-correspondent Rainfalls at San Francisco, in Lunar and Solar 
periods, from ‘July 1, 1849, to July1, 1872. R= Total fall; N= Normal percentage of 
rain, 
LUNAR MONTHLY || SOLAR YEARLY. 
; A | - 
Noy. Dec. Jan. Feb. Mar.-Oct. Yr. || 1849+3n* 1850}82 185143n Ay. 
RA? S| alas Wag * CNT ae | SERS REREACEE| ——A-— —— sales atta | 
eee Oe ee ee es ae a eee 
6.67 84 816 124 126 69 97 || 22.85 319 16.01 287 12.19 273 2097 
4.93 83 12.69 128 474 81 97 |} 28.41 314 14.94 264 6.12 194 267 
6.58. 82.) 6.16- 150 -5.07 — OF Oh 4 26.26 260 1115 242 9.84 155 228 
6.61 98 6.81 105 5.88 98 92 || 5.20 190 1445 238 390 165 198 
8.562 109 9.26 99 3.18 90 96 14.98 169 13.67 227 11.97 202 194 
4.73 121 564 84 4.49 92 104 16.81 163 9.97 200 14.57 220 189 
9.74126 279 75 6565 101 107 7.67 140 9,94 171 4,97 213 169 
7.96 125 7.55 86 455 111 108 10.08 117 8.50 140 15.382 203 147 
9:00 320-787 ST. 6:78 119 107 911 97 4.41 108 804 158 117 
7.08: Jib = 16 92° 0.51 116 403 4 438 69 5.63 84 2.58 86 78 
8.12 104 604 79 3.86 lll 97 3825 42 329 62 30 46 49 
$.91 115° 3.54 67 615 117 99 146° 238. 1,56: 44 4.07. 37. 35 
13.40 188 446 72 700 129 110 we dhe 2 St 30, 2L 20 
9.47 148 6.89 91 562 148 125 | 10 5 FO LO 08 8 9 
9.65 1387 7.84 1138 960 172 138 | Pa ly g 2 06 5 05 1 3 
9.41 118 10.79 126 11.10 169 134 i 00 ae 4 1 200 1 1 
3.87 86 803 128 4.98 183 1165 |! -00 0 00 1 +21 2 1 
407 78 9.40 126 342 111 105 || 05 0 02 Ue. 00 1 1 
7.92 861006 118 815 110 104 |} 01 af 02 0 .04 2 1 
6.34 86 6.69 101 3.99 97 96 28 2 300 ly 200 5 2 
6.17 82 647 92 3.67 72 85 ak 2 04 3. 419 9 4 
B.6l 84 6.96 94 226 55 88 || (eS us a 
Test 80 6.88 J00 Tiel 57 86 |) 0B 8 do 8 0B ye 
2 | 2.14 25 OL UL 2at 3r e 
4.31 89 5.52 93 392 76 85 
9.29 103 9.53 105 5.12 85 93 
. 21.8L 260 351 203 8.28 233 235 
7.09 105 6.94 1138 443 77 96 
26.52 300 20 82 261 25.381 307 290 
¥ 1849, °52, 765, °58, °61, ’64, '67, °70; 1850, °53, °66, ete., 1851, °54, °57, °60, ete. 
