Proceedings. 59 



of temperature from summer to winter, it would be seen that 

 the rise was more gradual than the fall. The lowest tempe- 

 rature may be expected about January 10th, and the maximum 

 about July 25th, continuing until August 10th, a period of 

 seven months ; but the decrease in temperature from August 

 10th to January 10th occurs in only five months. This law 

 of increasing and decreasing temperature is occasioned, I 

 apprehend, partly from prevailing north-easterly winds in the 

 spi-ing, and from the circumstance that the nights in spring 

 are often clear and cold, the radiation of heat being conse- 

 quently great at night, retarding the advance of temperature. 

 The earth is also less clothed in the spring than in the 

 autumn, and the clothing of the trees with leaves in the 

 autumn tends to retain the night-temperature. Although 

 on a clear summer's day the open heath has a much higher 

 temperature than the copse or the wood, on a clear night the 

 wood has a much higher temperature than the open heath or 

 field, proving that the temperature is much influenced by the 

 earth's clothing. The heat is retained while the leaves are 

 on the trees, but the leaves fall more rapidly in the autumn 

 than they develop in the spring, hence one cause of the more 

 rapid cooling of the earth's surface in the autumn. 



Rain. — At Eedhill the total fall of rain in the year was 

 31-51 in. The average annual amount during the last twenty 

 years, as recorded by me, is 31-28 in. 1886 may therefore be 

 regarded as a wet year. More rain falls at Eedhill than at 

 Greenwich, where the average annual fall is about 26-| in. 



Eain fell on 174 days. During the last twenty years, the 

 year in which the least number of days occurred on which rain 

 fell was 1870, 130 days. The greatest number of days was in 

 1872, 215 days. The average of twenty years gives 178 days. 

 The amount of rain in the year does not, however, always 

 correspond with the number of days on which rain may have 

 fallen, although the amount has some relation to the number 

 of wet days. The smallest quantity of rain which fell in any 

 year during the last twenty years was in 1884, when only 

 23-03 in. fell on 168 days. The largest quantity was in 1877, 

 when rain fell on 203 days to the extent of 39-07 in., but in 

 1883 rain fell on 201 days to the extent of only 29-81 in. 



