APPENDIX A 35 



(5o-7). The difference between the average temperature of 

 the warmest and coldest year recorded was only 2-5 for the 

 water. 



The highest mean temperature of the water for any month 

 was 6g-2 in September 1893, in a month with a low rainfall, 

 but in the year of the highest average air temperature. The 

 lowest mean temperature of the water was 32-4 for January 

 1891 (air 32'6), but the lowest air temperature was 29- 2 for 

 December 1 890, when the water had a mean of 333. 



The difference in average temperature of water for the 

 same month in different years was greatest in the months of 

 annual maxima and minima. The hottest June was I2'7 

 warmer than the coolest June ; the warmest January was i o-6 

 warmer than the coldest January. But it does not clearly 

 appear that at the time of annual average temperature the 

 difference was least ; for the warmest April was 9-3 and the 

 warmest September 12 '-3 above the temperature of the coldest 

 month of the same name. 



On the average the air temperature came nearest the water 

 temperature in the winter months, notably in November and 

 January, when they almost coincided, and the two tempera- 

 tures diverged most in the summer months, April to July, 

 when the difference averaged 23. During the twenty-two 

 years of observation the average monthly air temperature 

 was higher than the average monthly water temperature at 

 10 a.m. on forty-six occasions. Of these ten occurred in 

 January, nine in February, ten in November, and seven in 

 December, or thirty-six in the winter months ; four were 

 in March, one each in April, May, July, and August, and two 

 in October. In no June or September, between 1882 and 

 1903, has there been an instance of air being warmer than 

 water on the average of a whole month. Of course, in the 

 observations now recorded the comparison is made between 

 average air temperature for the whole twenty-four hours, and 

 average water temperature at 10 a.m. only. 



D 2 



