210, 



offer a few practical suggestions which have occun'ed to me whilst 

 reflecting upon the subject. 



The storms which pass over the British Isles are found generally to 

 act in strict accordance with the "cyclonic" theory. In many cases, 

 however, this accordance is not so obvious, and the phenomena become 

 highly complicated. This is a result which often happens when two 

 or more cyclones interfere — an event of very frequent occurrence. 

 When interferences of this description take place we have squalls, 

 calms (often accompanied by heavy rains), thunder storms, great varia- 

 tions in the direction and force of the wind, and much irregularity 

 in the barometric oscillations. These complex results are however 

 completely explicable by the cyclonic theory, as I have tested in several 

 instances. A very beautifid and striking example of a compound 

 cyclonic disturbance of the atmosphere, at this place, was investigated 

 by me in September, 1840, and found to be due to the interference of 

 three storms, in the manner shewn in the subjoined diagram : — 



The dotted line and the dates show the progress of the storms over 

 this locality, and the curved arrows the vortical or cyclonic movement, 

 from right to left, which is found to hold with regard to the storms of 

 the northern hemisphere. A glance will suffice to indicate the nature 

 of the meteorological changes which might be expected to occur at any 

 point upon the dotted line, or on parallel lines, diuing the passage of 

 the storms in question. The complicated veerings of the wind, the 

 risings and faUings of the barometer, the calms, irregular gusts and 

 occasional heavy showers, which prevailed for about a week, whilst this 

 system of cyclones passed over this locality, appeared at first quite 



