36 REPORT — 1856. 



the S.W. wind of the second neutralizes the N.E. wind of the first ; the wind is 

 feeble and the mercury rises. Nevertheless, the S.W. prevails on the 25th ; this 

 changes to W., and finally to N.W. on the 28th and 29th with almost continual 

 rain. These winds show that the centre of the second cyclone passed to the north 

 of Bordeaux, and therefore between Bordeaux and Teignmouth. 



In neither of these cyclones is the central barometric depression so extreme as is 

 usual in the great winter storms. This may probably arise from the confusion or 

 juxtaposition of the central spaces. 



On the Balahlava Tempest, and the Mode of Interpreting Barometrical Fluc- 

 tuations. By T. DoBSON, B.A. of St. John's College, Cambridge. 



In the month of November, 1854, the passage of a storm over the British islands 

 caused a considerable depression of the barometric column, beginning on the 11th 

 of November and ending on the 19th, as shown by the barometric curves which 

 accompany this paper. During four consecutive days of this period of diminished 

 atmospheric pressure, there occurred in the coal mines of Britain six fatal explo- 

 sions, at the following places : — on Nov. 13, at Old Park Colliery, Dudley, Worces- 

 tershire ; Nov. 14, Cramlington Colliery, Northumberland; Nov. 15, Bennett's 

 Colliery, Bolton, Lancashire ; Birchey Coppice Colliery, Dudley ; and Coalbrook 

 Vale Colliery, Monmouthshire ; Nov. 16, Rosehall Colliery, Coatbridge, N.B. 

 These facts alone render this storm worthy of especial attention, independently of 

 the notoriety which it has acquired from its disastrous effects on the allied fleets 

 and armies in the Crimea. The meteorological circumstances which characterized 

 the Balaklava tempest have been determined with unusual care and skill, from a very 

 great number of observations at stations spread over the whole surface of Europe, 

 by M. Liais, of the Imperial Observatory at Paris. In all probability, many years 

 will elapse before a great storm on land is subjected to an examination so rigorous 

 and complete as that undertaken by M. Liais, in the present instance. This storm 

 may therefore be adopted as the most satisfactory test that we are likely to have 

 for some time to come of the correctness of the principles of interpretation which 

 I have already applied to barometric fluctuations in my report on the relation be- 

 tween explosions in coal mines and revolving storms, — principles which flow directly 

 from the nature of cyclones. 



