Quantity of Rain. 
305 
TABLE XXXVII.— Quantity of Rain for each Month in 1843, by the Observatory Garden 
and Greenhouse Gauges. 
Month. 
Observatory 
Garden 
Greenhouse 
Gauge. 
Gauge. 
Gauge. 
January 
1-978 
2-00 
0°84 
February 
1-926 
1-95 ? 
0-95 
iviarcn 
u-yo 
U-7U 
April 
2-231 
1-95 
1-63 
May 
3-237 
3-17 
2-53 
June 
1-311 
1-24 
1-09 
July 
2-676 
2-47 
2-26 
August 
September 
2-752 
2-51 
2-36 
1-080 
1-00 
0-86 
October 
3-645 
3-73 
3-19 
November 
2-038 
1-82 
1-45 
December 
0-949 
0-66 
0-49 
Sums, 
24-757 
23-45 
18-35 
The quantity of rain for February, in the garden gauge, is estimated, the register for that month having 
been lost. 
The greatest quantity of rain in any month is that for October, being, by the Observatory gauge, 3-645 in. 
The least monthly quantity is that for March, being, by the same gauge, 0-934 in. The quantity of rain is a 
minimum in the solstitial and equinoctial months of 1843, maxima occurring in the intervening months. 
No conclusions can be drawn as to the cause of the differences of the sums for the Observatory and Garden 
gauges, as the gauges are not only at unequal heights above the level of the sea, but also above the soil. 
The results for the Greenhouse gauge shew, that such a position is sufficient to destroy the value of the 
instrument as a pluviometer. (See Introduction, page Iviii.) 
The greatest amounts of rain found in the Observatory gauge at noon, having fallen within the previous 
24 hours, for each month are as follow : — 
Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 
in. in. in. in. in. in. in. in. in. in. in. in. 
0-650 0-387 0-290 0-468 0-403 0-420 0-386 1-411 0-252 0-890 0-460 0-253 
The numbers of days in each month on which more than one- thousandth, one-hundredth, and one-tenth of 
an inch of rain was found in the Observatory gauge, are as follow : — 
More than 
Jan. 
Feb. 
March. 
April. 
May. 
June. 
July. 
Aug. 
Sept. 
Oct. 
Nov. 
Dec. 
0-001 
23 
22 
16 
19 
23 
16 
22 
19 
12 
30 
27 
17 
0-010 
14 
17 
11 
13 
17 
10 
14 
15 
6 
19 
16 
7 
0-100 
6 
6 
3 
9 
11 
7 
8 
8 
2 
10 
6 
2 
The variation of the numbers follows nearly the same law as the variations of the monthly sums of rain 
fallen. In 1843, more than one-thousandth of an inch of rain fell on 246 days, or on about 6 days out of 9 ; 
more than one-tenth of an inch fell on 1 59 days, or on about 4 days out of 9 ; more than one-tenth of an inch 
fell on 78 days, or on about 2 days out of 9. 
In dividing the monthly sums of rain by the number of days on which more than O001 inch fell, we ob- 
tain the following means for the quantity of rain which fell on days in which more than O001 was found in the 
Observatory gauge : — ■ * 
Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 
in. in. in. in. in. in. in. in. in. in. in. in. 
0-086 0-088 0-058 0-117 0-141 0082 0-122 0-145 0-090 0-121 0-113 0-056 
These quantities follow nearly the same law as the monthly sums. We may therefore conclude, that for 
those months which have the greatest number of rainy days, the mean daily fall of rain is greatest ; or, that 
the oftener it rains, it rains the heavier. 
MAG. AND MET. OBS, 1843. 4h 
