36 



DR HUGH ROBERT MILL ON THE 



lower in 188G, the latter in 1887. Taking the elate of mean air minimum to be the 

 middle of February, it appears about six weeks earlier than the water minimum. The 

 period of heating for the air is shorter than that for the water in comparison with the 

 period of cooling. In 1886 the period of air-cooling was 24 per cent., and in 1877, 

 32 per cent, longer than that of heating. 



The rate of change of temperature in the mass of the water is also a matter of interest, 

 considered with regard to its fluctuations with time. 



Table VI. — Rate of Change of Temperature in the Channel. 



Calculated from Curve. 



Calculated from Observations. 



Period. 



Days. 



Change of 

 Temperature. 



Do. 



per Day. 



Periods. 



Days. 



Change of 

 Temperature. 



Do. 

 per Day. 



1886. 





° F. 



F. 



1886. 









April 16-30, 



15 



+ 1-1 



+ 0-074 



April 16-June 19, . 



64 



4-5-4 



+ 0-084 



May 1-31, . 



31 



+ 2-9 



+ 0-094 











June 1-30, 



30 



+ 2-7 



+ 0-090 











July 1-31, . 



31 



+ 2-6 



+ 0-084 











Aug. 1-31, . 



31 



+ 3-1 



+ O-IOO 



June 19-Aug. 12, . 



53 



+ 5-0 



+ 0-094 



Sept. 1-30, 



30 



-1-4 



- 0-047 



Aug. 12-Sept. 22, . 



41 



+ 2-1 



+ 0-051 



Oct. 1-31, . 



31 



-2-0 



-0-065 











Nov. 1-30, 



30 



-1-6 



-0-053 









. 



Dec. 1-31, 



31 



-1-5 



- 0-048 



Sept. 22-Dec. 25, . 



94 



-6-0 



- 0-064 



1887. 









1886-87. 









Jan. 1-31, . 



31 



-2-0 



-0-065 











Feb. 1-28, . 



28 



-2-2 



-0-078 











March 1-31, 



31 



+ 0-6 



+ 0-020 



Dec. 25-M'arch 30, . 



95 



-4-2 



- 0-044 



April 1-30, 



30 



+ 1-1 



+ 0-037 



1887. 









May 1-31, . 



31 



+ 1-7 



+ 0-055 



March 30-May 4, . 



35 



+ 1-5 



+ 0-043 



June 1-30, 



30 



+ 3-0 



+ O-IOO 



May 4- June 17, 



44 



+ 3-0 



+ 0-070 



July 1-31, . 



31 



+ 3-7 



+ 0-I20 











August 1-31, 



31 



+ 2-5 



+ 0-083 



June 17 -Aug. 18, . 



62 



+ 6-5 



+ 0-105 



Sept. 1-30, 



30 



-1-1 



-0-037 



Aug. 18-Sept. 21, . 



34 



+ 0-6 



+ 0-018 



Oct. 1-31, . 



31 



-23 



-0-074 











Nov. 1-30, 



30 



-2-7 



- 0-090 







. 





Dec. 1-31, . 



31 



-2-6 



- 0-084 



Sept. 21 -Dec. 8, . 



78 



-6-0 



-0-077 



1888. 

















Jan. 1-31, . 



31 



-2-0 



- 0-065 



Dec. 8-31, 



1888. 



23 



-2-6 



-0-113 



Feb. 1-28, . 



28 



-1-5 



-0-054 



Dec. 31-Feb. 16, . 



47 



-2-5 



-0-053 



March 1-31, 



31 



-1-2 



-0-037 



Feb. 16-March 17, . 



29 



-1-8 



— 0-062 



April 1-30, 



30 



+ 0-2 



+ 0-007 



March 17-21, . , . 



4 



o-o 



o-ooo 











March 21-31, . 



10 



-o-i 



- O-OIO 



Table VI. gives the mean monthly rate of change calculated from the temperature 

 curve, and also the more irregular deductions for the intervals of time between actual 



