Barometric Wave, November 1847. 47 



formed of the vast extent these waves generally cover. The 

 transference of the points or lines of maxima and minima, as 

 existing in space and as determined by this mode of discussion, 

 will give the directions in which the waves are moving, and also 

 the rate of their progress. A new field of view opens upon the 

 mind in thus studying barometric phaenomena. The types 

 forming the first branch of the inquiry become inlets to the 

 knowledge of movements of vast extent, and of realities, which 

 although unseen by us. produce the most terrific commotions 

 in the atmosphere. The wave of which we have been speaking 

 has not passed over the United Kingdom, nor has it swept the 

 shores of sea-girt Britain, without leaving melancholy traces 

 of its progress. Could we ascend in our inquiries from the con- 

 templation of the rotatory storm, as determined by Redfield and 

 Reid, to the production of such storm by the crossing of two 

 large long waves, as suggested by Sir John Herschel in his 

 Report on Meteorological Reductions, from which we have 

 already quoted, an important step would be gained. Sir John 

 states*, " There is certainly one point of view in which some of 

 the phaenomena of revolving gales would seem capable of ex- 

 planation * * * >r=j and in which the}' would become traced up, 

 not to 'funnel-shaped revolving depressions' in the nature of 

 water-spouts, but simply to the crossing of two large long 

 waves running in different directions. The way in which a 

 rotary movement in an ellipse or circle, or in some other partly 

 oval and partly rectilineal figure, may result from the combi- 

 nation of two rectilineal movements of advance and recess, 

 will easily be understood by the analogy of the circular and 

 elliptic polarization of light, where rectilinear movements of 

 the aelherial molecules are conceived to be similarly combined. 

 Some features in such storms are strongly in harmony with 

 this view ; viz. the fact, that in them the direction of the wind 

 at a given locality never makes more than one rotation, and 

 not always that; and that in the central line of the storm's 

 progress, there is a simple and sudden reversal of direction. 

 On the other hand, it must not be concealed that some features 

 militate against it; for instance, the fact that such gales are 

 stated always to 'revolve' in one direction ; whereas on this 

 view of their origin, the changes of wind ought to be in oppo- 

 site directions, on opposite sides of the medial line." 



In an article which the writer communicated to Mr. Lowe 

 of Highfield Hou'-.e near Nottingham, and which is inserted 

 in that gentleman's work on Atmospheric Phaenomena, an 

 aitemjit has been made to exhibit the connexion, which there 



* Reports of the British Association for the Advancement of Science, 

 1843, p. 100. 



