224 OBSEEVATIONS ON THE WINDS. 



on its S.W. side. On the North side of this Anti-Cyclone, Cyclonic areas 

 frequently arise, moving away to the Eastward. On its S.E. side, near 

 Madeira, Cyclones are also occasionally formed ; these either work very 

 slowly to the S.W., or cross over towards the Strait of Gibraltar.* 



The lowest latitude of any centre of low pressure which has been dis- 

 tinctly traced in the North Atlantic Ocean is 6° 6' N., and there are eight 

 cases of Cyclonic Storms whose paths have been traced to points South of 

 lat. 10° N. Hard gales and violent squalls of wind sometimes occur 

 directly under the Equator.f 



(163.) Path or Track.— "We have before stated (158), that besides its 

 circular motion the Cyclonic Storm also moves forward bodily along certain 

 tracks, according to the locality in which it is found. The investigation 

 of the records of a very large number of West Indian Hurricanes has led 

 to the following conclusions with regard to the tracks which they generally 

 follow, though, as will be seen from the practical examples hereafter given, 

 no dependence can be placed upon any Storm following a certain track, so 

 much depending upon the meteorological conditions of the area surround- 

 ing it. 



Professor W. Ferrel well describes the progressive motion of a C3'cIone 

 as depending mostly upon the general motions of the atmosphere, but also 

 upon the tendency of the Cyclone to press towards the Pole. In the Trade 

 Wind latitudes the wind at the earth's surface is Westward, or at least 

 has a large Westerly component, and hence the Cyclones in these latitudes 

 are carried Westward by this Westward motion of the air, especially at 

 certain seasons ; and having likewise a tendency toward the Pole, the 

 resultant of the two is a Westward motion, inclined a little toward the 

 Poles, or in the Northern Hemisphere a motion about W.N.W. After 

 having arrived at the parallel of 20° to 33° or 35° in the Tropical calm 

 belt, where there is no Westward motion (according to the season), the 

 progressive motion is a Polar one mostly, but after progressing still nearer 

 the Pole, into the middle and higher latitudes, the general Eastward 

 motion of the atmosphere here, which is great in the upper regions, now 

 carries the Cyclone towards the East, and the direction of the progressive 

 motion, which is usually about E.N.E., is the resultant of this Eastward 

 motion and the motion towards the Pole. All well-developed Cyclones, 

 therefore, having their origin in the Tropics, have mostly a progressive 

 motion represented by a curve somewhat in the form of a parabola, as will 

 be seen from the diagram showing the courses of various Hurricanes. 



Padre E. P. B. Vines, of Havana, as the result of his study and long 

 experience of this subject, states that between lat. 10° and 15° N. a Hurri- 

 cane moves almost due West. 



In June and October its course changes rapidly to N.W. and North, 

 recurving about lat. 20° to 23°. 



In July and September it continues on its N.W. course to lat. 27° to 29° 

 before recurving. 



In August it continues on its N.W. course to lat. 30° to 32° before re- 

 curving. 



* " Weather," by the Hod. R. Abercromby, 1887. 



t Prof. E. Loomis, " On Areas of Low Pressure," American Journal of Science, 1885. 



