ON TUE SEASONAL VAraATIONS OF TEMPEEATURE. 



457 



A. Observations not recorded in full in this Report. 



These observations were, as a rule, made by skilled observers for 

 Bpecial purposes, and the abstracts were prepared specially for this report 

 by the investigators, to whom the thanks of the Committee are very 

 cordially given. 



River Cherwell at Oxford. 



Observations of the temperature of the Cherwell have been made 

 regularly every morning since 1878 by Mr. Edward Chapman, M.A., 

 P.L.S., of Magdalen College, Oxford. The ordinary meteorological 

 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 9 a.m., 

 the air-temperature is the mean of the maximum and minimum thermo- 

 meter 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-tempera- 

 ture for the ten years was 48°'9, the average water-temperature at 9 A.M. 

 60°-3, or 1°'4 warmer than the air; the mean annual rainfall for these 

 years being 24-79 inches. The average monthly means are shown in the 

 Curve below. The year of lowest air-temperature was 1887, with 47°"6, 



Curve of Temperature of Cherwell. Mean of 10 years. 

 Air Wccta- RazTi/kZL ^ 



2 inches 



1 inch 



inch 



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°'0, when the mean air-temperature was 47°'9 and the 

 rainfall 27-39. The highest air-temperature was 50°-9, the mean of 1884, 

 when the water-temperature was also highest, 51°-5, ; nd the rainfall was 

 19-48 inches. In 1890, the year of lowest rainfall, when only 17-02 inches 

 fell, the temperatures of air and water were almost at their average (49°-0 

 and 50°-8 respectively) ; while in 1886, which was the wettest year, with 

 ■ 3212 inches of rain, the air-temperature was also normal (49°-0), but the 



