486 REPORT-—1904. 
close to show that the stations from which the monthly means are deduced are 
fairly representative. 
Although 502 stations may be a sufficient number from which to compute the 
rainfall of England for a given period, a much longer period than ten years is 
required for an estimate of the true average to be arrived at. For this the 
shortest period which can be taken is thirty years, and forty years give a more 
satisfactory result. But when we come to work at this period the difficulty 
arises that the number of consecutive records is inadequate. This difficulty may 
to some extent be overcome by computing the probable rainfall for the larger 
number of stations from that at the smaller number for a long period. 
The following table gives the rainfall in 5-yearly periods from 1861 to 1900 
at 50 stations, 18 being in the Northern counties, 11 in the Midland, 10 in the 
South-Eastern, and 11 in the South-Western :— 
Taste Il.—Mean Annual Rainfall in England, 1861-1900. (50 Stations.) 
i} 
Counties 1861-65 |1866-70 |1871-75 | 1876-80 | 1881-85 | 1886-90 | 1891-95 | 1896-1900 | 1861-1900 
Tns. Ins. Ins. Ins. Ins. Tos. Ins. Ins, Ins. 
Northern . .]| 34°43 37°13 37°75 38°92 38°22 33°34 34:98 35°68 36°31 
Midland . : 22°40 24:07 26°90 29°35 27°04 23°79 23°82 22°62 24:99 
South-Eastern . 25°85 27°80 28°39 31°62 27°60 25°80 27°45 27°72 25°03 
South-Western . 31°23 33°65 37°57 38°75 35°46 30°55 31°86 3155 33°83 
as ae 
England . «| 29°36 31°63 33°45 35°51 33°03 29°14 30°32 29:91 3154 
The mean rainfall at the 50 stations for the ten years 1881 -90 being 31:08 inches, 
and for the forty years 1861-1900, 31:54 inches, and the mean rainfall at the 502 
stations for the ten years 1881-90 being 31-76 inches, it follows by proportion that 
the mean for the forty years for the 502 stations would be 32:23 inches, or there- 
abouts. 
Other periods may also be taken, and the following table gives the results of 
comparison with the ten years 1881-90 of the mean rainfall at 16 stations for 
sixty years, at 50 for forty years, and at 100 for twenty-five years :— 
Taste I1I.—Mean Annual Rainfall in England for Various Periods compared 
with 1881-90. 
16 Stations 50 Stations 100 Stations 502 Stations 
Counties o_o OO | 
No. 1841-1900 | 1881-90 | No.) 1861-1900 | 1881-90 | No.| 1866-90 | 1881-90 | No.| 1881-90 
Ins. Ins. Ins. Ins. Ins. Ins, Ins. 
Northern . 36°45 36°68 | 18 36°31 35°78 40| 39°80 38°54 | 184] 36°16 
6 
Midland . -| 3 25°51 25°96 | 11 24:99 25°91 | 20| 26°96 25°99 | 106} 26°29 
South-Eastern . | 3 29°08 2820 | 10 25°03 26°70 | 20} 27°79 26°19 | 99] 26°80 
South-Western. | 4 37°53 36°08 | 11 33°83 33°00 | 20) 37°66 35°86 | 113) 34°08 
England . - | 16 33°21 32°93 | 50 31°54 31°08 | 100} 34-40 33°02 |502| 31°76 
By proportion the probable mean rainfall for the twenty-five years 1866-90 
(a wet period) comes out as 33:09 inches, and for the sixty years 1841-1900 as 32:03 
inches. It must be understood that the results for the 16, 50, and 100 stations are 
considered of value only for comparing one period with another, and not as giving 
in themselves a true indication of the actual mean rainfall of the periods to which 
they relate. 
