428 THE PHYSICAL GEOGRAPHY OF THE SEA. 



observers be at c", c?, and e, and let c" and d be eacli several hund- 

 red miles from A, Now, then, will not the air at c" and d blow 

 north and east as directly for the place of low barometer as it 

 would were that place an oblong,^ J., instead of a disc, as per the 

 arrows ? And why should it be a disc in preference to an ellipse, 

 a square, an oblong, or any figure, be it never so irregular ? The 

 ^^'J^^ trade-winds answer, and show 



c" fy . j.--.^.£™..^--a^ ..™ ^1^^ equatorial calm belt — an ob- 



\^^_^-' long — as their place of meeting. 



/ A fi / But the cyclonologists, instead 



•v./' At of permitting the wind at the 



/ c^ §// distance c" to blow to the east, 



and at d to blow to the north, 

 merely because there is a low 

 barometer east of c" and north of c/, require it so to blow because, 

 by their theory^ there is a low barometer east of c? and south of c" 1 

 Thus, to reach its theoretical place of destination, the wind must 

 blow in a direction at right angles to that destination ! It would 

 require a rush of inconceivable rapidity so to deflect currents of 

 air while they are yet several hundred miles from the centre of 

 gyration. Moreover, the two cyclonologists, c" and o?, would dif- 

 fer with each other as to the centre of the storm. The one in ship 

 d would place it to the east of him, or in that direction, but the 

 other, c", would place it to the south of him, as in the direction c' , 

 The gyrating disc of a cyclone can never, I apprehend, exceed 

 a few miles in diameter. On shore we seldom find it exceed- 

 ing in breadth as many rods, in most cases not as many fath- 

 oms, as its advocates give it miles at sea. I think the dust-whirl 

 in the street is a true type of the tornado (cyclone) at sea. Im- 

 agine such a case to occur in nature as the one just supposed. 

 With the observations of d alone before him, the cyclonologist 

 would say the storm was traveling west, but passing north ; with 

 the log of c", he would say it travels west, but will pass south of 

 us. By the rule, ship d would be led toward the real track of the 

 storm, i. e., into danger, and ship c away from it.* 



800. There are in the various parts of the storm at least three 

 The three forces, forccs at work in effecting a change of wind, as ob- 



* See letter to Commodore Wiillerstorf, p. 457, vol. ii., 8th ed. Maury's Sailing 

 Directions. 



