376 REPORTS ON THE STATE OF SCIENCE, ETC. 
are classified geographically, first by Districts (groups of counties), then 
by River Divisions. Ten-year sheets for stations in the same River 
Division are filed in sequence, the file thus forming, when completed, a 
ten-year history of the rainfall in each River Division of a District. This 
arrangement makes it possible readily to turn up the rainfall at any station 
in any month and year. 
For the great majority of stations the space allotted in British Rainfall 
is a line in Part III giving the diameter of the gauge, the height of ‘its 
rim above ground, the height above sea-level, the average rainfall (if known), 
the year’s total, the number of rain-days and the number of wet-days. 
Such data were published for 5,329 stations in 1931, 5,316 in 1930, and 5,180 
in 1929. The number has been in the neighbourhood of 5,o00 for the 
past twenty years. Unfortunately the distribution of stations is very 
uneven, the sparsely populated districts being poorly represented. "The 
number of records per 100 square miles of area is as high as 28 in Middlesex, 
but is under 1 in parts of Scotland and Ireland. About 300 new stations 
are enrolled every year, and about the same number terminate. The 
average ‘ life’ of a station is therefore about eighteen years. A frequent 
cause of the cessation of a record is the death of the observer or his removal 
to a new district. In some cases it is possible to arrange for the record to 
be continued by a relative or the new resident, and every effort is made to 
ensure such continuity, more particularly in the case of long records. 
The records for all stations are scrutinised in relation to ‘ heavy falls on 
rainfall days’ (British Rainfall, Part II, Section 7), but selections of stations 
are made for the purpose of studying the special aspects of rainfall dealt 
with in other sections of the volume. For example, 100 stations are used 
for the purpose of Part II, Section 2 (number of rain-days and wet-days), 
Section 3 (droughts), and Section 4 (rain-spells), 400 stations for Section 8 
(monthly rainfall, Table XX), and 150 stations for Tables XXI and XXII, 
giving the monthly and seasonal fall as a percentage of the average. 
RAINFALL DATA IN OTHER PUBLICATIONS. 
Reference has already been made to the Monthly Weather Report and 
the Meteorological Magazine. Other Meteorological Office publications 
containing rainfall data are the following :— 
The Weekly Weather Report gives weekly and seasonal totals of rainfall 
at each of sixty stations, together with the heaviest fall in each week and 
the relation of the weekly total to the normal. General values !! for Districts 
are also given. 
The Observatories Year Book contains hourly values of rainfall at the four 
Observatories: Aberdeen, Eskdalemuir, Richmond and Valentia; also 
monthly totals of duration in each hour. For Richmond, Surrey, daily 
values of water level in a well are given. 
The Book of Normals (M.O. 236, Section V) contains monthly and 
annual values of average rainfall for the period 1881-1915 at 578 stations, 
and also general averages for the British Isles and its major divisions. 
Monthly averages of the number of rain-days at certain stations will be 
11 In the nomenclature of the British Rainfall Organization ‘ general value’ 
means the average for an area. In the Weekly Weather Report the quantity 
represented by the weekly (or seasonal) general value for a District is the space- 
average of the percentage of normal rainfall in a given week (or season) at five 
selected stations in that District. This value is briefly referred to as the ‘ District 
value. . 
