Proximate Causes of certain Winds and Storms. 249 



their direction is reversed ; to the distance seaward of about three 

 hundred miles, they blow towards the land, and nearly at right angles 

 to the coast. 



Halley notices a tract between the 4th and 10th degrees of north 

 latitude, and the longitudes of 17° and 23°, " wherein it were im- 

 proper to say there is any trade wind, or yet a variable one, for it 

 seems condemned to perpetual calms, attended with terrible thunder, 

 lightning and rains, so frequent that our navigators, from them, call 

 this part of the sea, the Rains ; the little winds they have are only 

 some sudden uncertain gusts of very short continuance and less ex- 

 tent, so that sometimes each hour there is a different gale which dies 

 away into a calm before another succeeds ; and in a fleet of ships in 

 sight of one another, each will have the wind from a different point 

 of the compass ; with these weak breezes, ships are obliged to make 

 the best of their way to the southward, through the aforesaid 6°, 

 wherein it is reported some have been detained whole months for 

 want of wind."* 



Instead, however, of being confined to these longitudes, it would 

 appear that either a total cessation or a remission of the force of the 

 trades is observed between the latitudes specified throughout nearly 

 the whole extent of both the Atlantic and Pacific : the effect being 

 however more distinctly marked and perceptible in the former than 

 in the latter ocean. A few quotations are given ; it would be easy 

 to add largely to their number. 



" The southern trade wind being cooler in like latitudes than the 

 northern, usually passes the equinoctial into the northern hemisphere. 

 The northern trade wind falls considerably short of it, as earlier at- 

 taining the maximum of heat. Between them is the region of varia- 

 ble winds, light airs and calms, attended with frequent squalls and 

 rain ; an uncertain wavy zone lying between the times of their influ- 

 ence. It is the tract in which the highest temperature prevails 

 throughout the year ; not at the equinoxes only, the sun being then 

 vertical, but also when he is distant at the tropics. In this warm and 

 damp region of the middle Atlantic, situated in the vicinity of the 

 equator," etc.-j- 



" After a most rapid run of several days, we reached the "swamp," 

 as the captain calls the calm and rainy latitudes, between the north- 



* Philosophical Transactions for 1686. 



t Colebrooke's Meteorological observations in a Voyage across the Atlantic, in 

 Brando's Journal. 



