Quantity of Rain. 



30/ 



TABLE XXXVII.— Quantity of Rain for each Month in 1843, by the Observatory Garden 



and Greenhouse Gauges. 



Month. 



Observatory 

 Gauge. 



Garden 

 Gauge. 



Greenhouse 

 Gauge. 



January 



February 



March 



April 



May 



June 



July 



August 



September 



October 



November 



December 



in. 



1-978 

 1-926 

 0-934 

 2-231 

 3-237 

 1-311 

 2-676 

 2-752 

 1-080 

 3-645 

 2-038 

 0-949 



in. 



2-00 



1-95? 



0-95 



1-95 



3-17 



1-24 



2-47 



2-51 



1-00 



3-73 



1-82 



0-66 



in. 



0-84 

 0-95 

 0-70 

 1-63 

 2-53 

 1-09 

 2-26 

 2-36 

 0-86 

 3-19 

 1-45 

 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 suificient 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. 



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 159 days, or on about 4 days out of 9 ; more than one-tenth of an incli 

 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 0*001 inch fell, we ob- 

 tain the following means for the quantity of rain which fell on days in which more than 0*001 was found in the 

 Observatory gauge : — 



Jan. Feb. March. April. May. June. July. Aug. Sept. Oct. Nov. Dec. 



0-086 0-088 0-058 0-117 0-141 0-082 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. 



1843. 4h 



MAG. AND MET. OBS, 



