194 MR ALEX. BUCHAN ON THE STORMS OF WIND WHICH OCCURRED 



that fog prevailed. When r is attached to any of the above letters, rain fell at 

 that station sometime during the previous twent} r -four hours, but was not falling 

 at the time of observation. The state of the sky at several places was not known. 

 These places are marked with an asterisk, and R in such cases means that it rained 

 sometime during the previous twenty-four hours ; but whether it was raining at 

 the time of observation or not cannot be learned from the returns. 



The direction of the wind (Table V.) is indicated on the maps by arrows re- 

 presented flying with the wind. The force of the wind is shown (1.) by plain 

 arrows — >, which represent light air to a moderate breeze ; (2.) by arrows 

 feathered on one side only ^-*, which represent a fresh breeze to a fresh gale ; and 

 (3.) by arrows feathered on both sides >-*, which represent a strong gale, storm, 

 tempest, or hurricane. A calm is shown by O. In the tables the force of the 

 wind is shown by the different types employed, as there explained. 



The observations comprehend four periods, viz., (1.) from the 2Gth October to 

 the 12th November ; (2.) from the 20th to the 26th November ; (3.) from the 30th 

 November to the 5th December; and (4.) from the 14th to the 18th December 

 — in all thirty six days. Maps were constructed, as described above, for each of 

 these days. A selection from these accompanies this paper Plates XIII. to XVIII. 

 give the barometric pressure, the temperature, the state of the sky, and the 

 winds, as observed on the mornings of the 30th and 31st October, and the 1st, 

 2d, 10th, and 11th November. Plates XIX. to XXI. give only the observations 

 of the barometer and winds on the mornings of the 28th and 29th October, the 

 3d, 4th, and 12th November, and the 1st, 2d, 3d, 4th, 5th, 16th, and 17th 

 December. 



Observations of the Barometer. 



The observations of the barometer are the most important of all the observa- 

 tions, since it is within the area where the barometer falls to some extent below 

 the average that storms occur. Speaking roughly, the mean atmospheric pres- 

 sure for these months is 29 9 inches. Therefore, the space comprehended within 

 the isobarometric line 297, and the other lines showing a less pressure, may be 

 called, for convenience' sake, the area of low barometer. Hence, while we trace 

 the progress of these low pressures over Europe from day to day, we trace at the 

 same time the progress of the storms. 



A brief account of these lines is desirable, to give some idea of the extent 

 and course of the storms. An area of low barometer occupied the greater portion 

 of the northern half of Europe, from the 28th October to the 9th November, 

 during which time its eastern limit advanced slowly and steadily eastwards from 

 Norway to the Ural Mountains ; while its southern limit, having first oscillated 

 backwards and forwards over the space lying between Spain and Ireland, ulti- 

 mately moved northward, and left Europe by the North Cape. During this time 





