226 



J. nOPKINSON — REPOET ON THE 



observers are most required I purpose to give with a future report 

 a map showing the position of the rain-gauges in the county. 



Particuhu's of the gauges, with the names of the observers, and 

 the monthly and annual rainfall (including melted snow) at each of 

 the stations, are given in the accompanying tables (pp. 224, 225). 



In the form of these tables I have made some alterations from 

 the similar tables in previous reports. To the table showing the 

 "Hertfordshire Rainfall Stations" have been added the river 

 districts, the latitude and longitude of each station, and a column 

 showing the method by which the height of each gauge above mean 

 sea-level (Ordnance datum) has been determined. The symbols are 

 those used by Mr. Symons in 'British Ilainfall,' ^ signifying that 

 a series of levels has been taken to the gauge from an Ordnance 

 bench-mark, T that the height has been ascertained approximately 

 from the same source, L that levels have been taken to the gauge 

 from some datum other than Ordnance mean sea-level, and B that 

 the height has been taken by the barometer. The latitude and 

 longitude are given approximately in order partly that the observers 

 may correct any error in the position assigned to their gauges before 

 the proposed map is prepared.* 



To the table of monthly and annual rainfall a column giving the 

 number of days on which -01 inch of rain, or more, fell during the 

 year, has been added, and the minor river-districts have been 

 omitted, being transferred to the first table. 



The rainfall will be seen to have been, as in 1876, very un- 

 equally distributed over the year. May, August, and November, 

 were the wettest months, the fall in each month exceeding four 

 inches, and the mean for the three being 4*66 ins. ; then follow 

 April, June, and October, each with a fall exceeding two inches, 

 and the three having a mean of 27 1 ins.; and lastly, in the six 

 remaining months — January, February, March, July, September, 

 and December — the fall varied from about an inch to an inch and 

 a half, and their mean fall was only 1-29 in., about one-fourth the 

 mean of the three wettest months. 



The next table gives the mean rainfall for the year for each of 

 the larger divisions or main river-basins, and also for each of the 

 smallerdistricts or lesser river-basins in which we have observers. 



Ouse ....25-29 



( Lower Colne 33-99 



( Bulborne 31-38 



Ivel 27-65 



Cam 22-94 



Lea. 



f Lower Lea 32-63 



I Upper Lea 29-76 



00 iqJ ^liiiuam 29J4 



■■^^'^'^S Ash 28-70 



! Beane 2-5-80 



[liib 28-96 



The relative proportion of the rainfall in the larger divisions will 

 be seen to be the same as during the two previous years, the basin 

 of the Ouse having the least, that of the Lea having the next, and 

 that of the Colne having the greatest fall. 



Of the 26 observers 21 give the number of days in each month 



* I wish particularly to draw the attention of observers to these figures. 



