Lxxiv BIRDS OF DUMFRIESSHIRE 
The strongest prevailing wind is westerly, and cyclones 
passing over the county almost invariably travel from 
SW or SSW. to NW. and N. Snowstorms, after the new 
year, regularly come from the SE., or SSE. by E. ; 
Ind it is interesting to note that Sir WUham Jardme, m 
a letter to his friend P. J. Selby in 1836, records a snow- 
storm from the south-west as most unusual* Gales from 
the north occur at rare intervals, and are extremely 
destructive to timber, notably the one on January 25th-27th. 
1884, when many woods in Upper Nithsdale were laid low. 
An idea, which cannot be entirely proved, exists locaUy 
that our weather runs in cycles extending over periods of 
thirty-three years. Throughout the last quarter of a century 
or so, the occurrences of certain species of birds rare to 
Dumfriesshire have been disappointing. Previous to that 
time, possibly about 1880, one of these thirty-three year 
periods may have terminated, since when we have been 
experiencing the contrary cycle of northerly and easterly 
winds continued long into spring, which has been unfavour- 
able to the appearance of what were former visitants 
Although weather phenomena do not entirely control 
migration, yet they affect the general increase or diminu- 
tion in the numbers and species of birds occurring during 
such periods, and only time and observation wiU show the 
validity of the existing beUef that our weather runs m thirty- 
three year cycles. In connection with this speculation, 
it is interesting to note that Mr. Andrew Watt writes on this 
subiect : " In Russia we have a great country whose internal 
trade is dependent on its navigable rivers, which are frozen 
during the winter months. The dates of the opening and 
closmg of these rivers are known with tolerable certainty 
for the last two hundred years, and appear to show that 
exceptionaUy cold years occur at intervals of from thirty 
to thirty-five years, and exceptionaUy warm years within 
a similar period."t 
• Sir W. Jardine, in litt.. to P. J. Selby, February 1st, 1836. 
f Scottish Oeographical Magaziw, April, 1908, p. 186. 
