TORNADOES. 145 



ward in the vicinity of parallel 50° N. The diameter of the storm's path varies 

 from several hundred to over one thousand miles. At the immediate centre of the 

 storm there is a dead calm, a most fatal place for ships to be caught. At no 

 point without the storm's centre does the air actually move or whirl in a circle, 

 but there is a cyclonic tendency of the atmosphere about the region of barometric 

 minima, viz : where the barometer is the lowest. Upon taking a number of 

 points, located here and there in the four quadrants of the meteoric disturbance, 

 it will be found that in the northeast quadrant the winds are from southeast to 

 northeast; in the northwest quadrant, from northeast to northwest; in the south- 

 west quadrant from northwest to southwest, and in the southeast quadrant, from 

 southwest to southeast. 



Again I repeat, a cyclonic tendency only. The barometer is a very impor- 

 tant factor in all calculations bearing upon a determination of the character and 

 approach of the cyclone at any point in the parabolic course of the storm. The 

 wind very rarely reaches either an estimated or measured velocity of 100 miles 

 per hour. The maximum velocity generally ranges from sixty to eighty miles 

 per hour. As a rule there is no sudden, overwhelming dash of the wind, but a 

 gradual approach or increase of movement which eventually culminates in a fierce 

 intensity sufficiently powerful at times to destroy buildings or sink the largest 

 ships. Cyclones occur most frequently in the months from August to November. 

 In the China and Japan Seas this class of wind storms are called typhoons. In 

 general, as to their place uf origin, cyclones form south of the Tropic of Cancer, 

 between the belt of calms and the southern limit of the trade winds; sav briefly, 

 in the vicinity of 10° N., 50° W. This region coincides with the zone of con- 

 stant rainfall, where evaporation is very rapid, cloud formation exceedinsily brisk, 

 the air almost constantly saturated with moisture, and heavy condensation a regu- 

 lar feature of the day. Typhoons form south of the Tropic of Cancer and in the 

 vicinity of the Philippine Islands, moving thence northwestward to the Asiatic 

 Coast and then curving to the northeast over the adjacent seas and islands. As 

 to the character of the region in which they form the same remarks apply as in 

 the case of cyclones. 



Tornadoes. — Comparing with the tornado which is truly and invariably a 

 land storm, we find this peculiar atmospheric phenomenon possessed of the fol- 

 lowing prominent characteristics : A path varying in width from a few yards to 

 eighty rods. The general direction of movement of the tornado cloiid is invaria- 

 bly from a point in the southwest quadrant to a point in the northeast quadrant. 

 The tornado cloud assumes the form of a funnel, the small end drawing near 

 to or resting upon the earth. This cloud or the moving air of which it is. 

 the embodiment, revolves about a central, vertical axis, with inconceivable 

 rapidity, and always in a direction contrary to the movement of the hands of a 

 watch. The destructive violence of the storm is sometimes confined to the imme- 

 diate path of the cloud, as when the small or tail end just touches the earth. 

 While on the other hand as the body of the cloud lowers, more of it rests upon 

 earth, the violence increases and the path widens to the extreme limit. The 



