312 Mr Redfield's Observations on the 



creased by hourly entries of the precise height of the mercu- 

 rial column, in a table prepared for the purpose. Its move- 

 ments, unless carefully recorded, often escape notice or recol- 

 lection ; which may easily happen at those times when a dis- 

 tinct knowledge of its latest variations might prove to be of 

 the greatest importance. 



In the foregoing statements our design has been to designate 

 in a summary manner the principal movements which, in these 

 regions at least, constitute a storm ; and we do not attempt to 

 notice the various irregularities, and subordinate or incidental 

 movements and phenomena of the atmosphere with which a 

 storm may chance to be connected, or which may necessarily 

 result from such violent movements in a fluid which is so tenu- 

 ous and elastic in its character. It may be remarked in general, 

 that the most active or violent storms are usually the most regular 

 and uniform in the development of those characteristic move- 

 ments which we have already described. It is also probable, that 

 the vortex or rotative axis of a violent gale or hurricane, oscillates 

 in its course with considerable rapidity, in a moving circuit of 

 moderate extent, near the centre of the hurricane; and such an 

 eccentric movement of the vortex may, for aught we know, be 

 essential to the continued activity or force of the hurricane. 

 Such a movement will fully account for the violent Jlazcs or 

 gusts of wind, and the intervening lulls or remissions, which are 

 so often experienced towards the heart of a storm or hurricane, 

 wljen in open sea ; but of its existence we have no positive evi- 

 dence. 



In Purdy's Memoir of the Atlantic Ocean it is stated, " That 

 while one vessel has been lying to in a heavy gale of wind, an- 

 other, not more than thirty leagues distant, has, at the very 

 same time, been in another gale equally heavy, and lying to 

 with the wind in an opposite direction." 



This statement is obviously to be understood as applicable 

 to two vessels falling under the two opposite sides or portions 

 of the same storm, where the wind in its regular circuit of ro- 

 tation must, of course, blow from the opposite quarters of the 

 horizon. We will suppose one of the vessels to be at A and 

 the other at B, in the annexed figure. The storm in pursuing 



