218 OBSEEVATIONS ON THE WINDS. 



Vines, of Havana ; Professors Wojeikof, Mohn, and Hildebrandsson ; 

 Messrs. Blanford, Elliott, and Willson, in India ; Dr. Doberek and Pere 

 Dechevrens, in China; Mr. Knipping, in Japan; Messrs. Birt, Jinman, 

 Evans, Scott, Buchan, Ley, and Toynbee ; and Professor Ferrel and 

 Lieutenant Hayden, in the United States. The writings of these gentle- 

 men, with those of numerous others, are chiefly to be found in various 

 periodical publications, and have been used in the compilation of the 

 following remarks, which, it is hoped, will be found to contain the essence 

 of the subject, though there are difficulties in reconciling the many con- 

 tradictory and confusing statements. 



(153.) Character. — Although the " Law of Storms " is now fully recog- 

 nized, opinion is not yet unanimous as to the real character and con 

 dition of these remarkable meteors. Eeid, Eedfield, and others, contend 

 that they are real vortices — currents of air revolving round a progressive 

 centre ; others, as Thom and Meldrum, contend that the wind blows in 

 spirals around this centre; Espy, that the wind blows toward the centre ; 

 others, again, consider that the vertical motion of the air will explain many 

 of the phenomena. Jinman considers that, as the air is blowing away 

 from one area, another current necessarily blows towards and into that 

 area, causing the peculiar features of these Hurricanes. It would be out 

 of place, and far too discursive for this work, to discuss at length these 

 various propositions ; they may readily be found in the numerous works 

 extant. 



One more remark may suffice. Is it not possible, nay, probable, that 

 each of these theories may be correct as to individual Cyclones, which 

 may be (and are) of such varied character as not to be reducible in all 

 cases to a fixed rule ? However, it is certain that in many examples the 

 true Eevolving Storm is the proper appellation. 



(154.) Rotation. — One fact with regard to these Storms appears to be 

 now all but indisputable, and that is the rotary or gyratory character of 

 the winds round a circular, or nearly circular, area or vortex of low baro- 

 metric pressure, which moves forward at the same time along certain 

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

 rotary character of the winds, simultaneous observations at different 

 positions during the progress of these Storms show there can be no doubt 

 that the winds which formed them were rotating round central areas. 

 The way in which the wind veered at all the places over which it passed, 

 cannot be explained on any other supposition. The depression of the 

 barometer within the areas of the storms, and the circumstance that the 

 depression was greatest everywhere at or near the centre, also indicates 

 another important feature, viz., that there is a diminished atmospheric 

 pressure within the whole area of a Cyclone, and lowest of all at the centre. 

 The diminished weight of the atmosphere at the places passed over by the 

 Cyclone may be accounted for by the suction which draws air towards it 

 from all quarters and the effect of which is necessarily to produce revolving 

 currents ascending spirally towards the area in the upper regions of the 

 atmosphere where a vacuum or great rarefaction originato,!. 



In the paper referred to in (156) is a description of a Waterspout which 

 w:.3 seen to extend upward to a height of 1,700 feet, and of several Dust 



