PRESIDENT'S ADDRESS. 13 



METEOROLOGY. 



The year 1916 was, generally speaking, a wet one in this 

 country, the rainfall being far in excess of the average at 

 most stations, and slightly below it at only a few. The excess 

 occurred chiefly in the S. of England, the centre of Scotland, 

 and the S.W., N.W., and E. of Ireland. The fall at Monte- 

 video, Chickerell, in 1916, was 34.10in., being 1.62in. less than 

 in 1915, but 4.47in. above the average for 18 years, which was 

 29.63in. at that station. It is remarkable that the two highest 

 falls in 24 hours during 19 years' observations should have 

 been recorded there in the same year, viz., one of 2.52in. on 

 August 29, and one of 2.00in. on December 20th, 1916. Before 

 that, the highest fall was 1.98in. on October 23rd, 1915. June 

 was an unusually cold month, and with the exception of June 

 19th, 1903, the Greenwich records show no June day colder 

 than June 12th, 1916, for 75 years, the thermometer not having 

 exceeded 50. The early part of the year 1917 has also been 

 cold, with long continued frost, and very low temperatures 

 from 2 upwards were recorded in different parts of England. 

 Frost occurred on 52 nights in the 3 first months, as well as 

 often in April. Some interesting aeroplane observations on 

 clouds tend to show that cirrus and cirro-stratus consist of 

 thin snow. When cumuli attain a height of 6,000 

 10,000 feet from top to bottom, they develop into thunder- 

 storms. The war has given much opportunity of studying 

 the propagation of sound in the atmosphere. The noise of 

 the firing has been heard at great distances, the highest I 

 have seen recorded being the firing in the Somme valley, 

 which is stated to have been heard at Winchester and 

 Ringwood (200 miles) and at Wendling in Norfolk (220 

 miles). The spring and summer are the best seasons for 

 transmitting sound, the winter the worst. There appears to 

 be generally an area of irregular shape, over which the sound 

 is audible, surrounded by a silent ring-shaped area, outside 

 which latter the sound is again audible. This " silent 

 region " varies in its distance from the source, but at the 



