34 HISTORY OF THE DAUBENY LABORATORY 



temperatures of the Cherwell, but to suggest the range of 

 deviations from normal seasonal temperatures to be expected 

 in any case. Thus we are warned not to assume the mean 

 of one or two years as being the real mean temperature of 

 any exposed body of water' (British Association Report for 

 1891, p. 19). And the second series of averages for twelve 

 years, which we now publish, demonstrates this still more 

 clearly. 



Observations of the temperature of the Cherwell were 

 made regularly every morning since 1878 by Mr. Edward 

 Chapman or by his assistant, and have been continued since 

 his resignation in 1894, up to date. The ordinary meteoro- 

 logical observations having been made at the same time, make 

 it possible to compare river temperature, air temperature, and 

 rainfall. The river temperature recorded below is the mean 

 of daily observations at 10 a.m., the air temperature is 

 the mean of the maximum and minimum thermometer in 

 the shade for the previous twenty-four hours, and the rainfall 

 is the amount in inches which fell in the previous twenty- 

 four hours. 



The length of this series of observations gives it peculiar 

 value in affording an indication of average conditions. The 

 average air temperature for the twenty-two years was 49\5, 

 the average water temperature at 10 a.m. 5o-9, or i-4 

 warmer than the air ; the mean annual rainfall for these years 

 being 23-6 inches. The year of lowest air temperature was 

 1887, with 47-6, the average water temperature for that year 

 being 49-8 and the rainfall 18-78 inches, very exceptionally low. 

 The lowest mean water temperature was in 1888, 49-o, when 

 the mean air temperature was 47-9 and the rainfall 27-39 

 inches. The highest air temperature was 5i-3, the mean of 1893, 

 when the water temperature was also highest, 53-5, and the 

 rainfall was 16-51 inches. In 1890, the year of the next lowest 

 rainfall, when only 17-03 inches fell, the temperatures of air 

 and water were almost at their average (49-o and 5o-8 respec- 

 tively); while in 1903, which was the wettest year, with 35-14 

 inches of rain, the air temperature was nearly normal (5o-r), 

 and the water temperature was also very near the average 



