78 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



have been put in motion by the same power ; tbey meet Y^tb equal 

 force ; and, therefore, at their place of meeting, they are arrested 

 in their com'se. Here, therefore, there is a calm belt, as well as at 

 Capricorn and Cancer. Warmed now by the heat of the smi, and 

 of vapour in the process of condensation, and pressed on each side 

 by the whole force of the north-east and south-east trades, these 

 two hypothetical particles, taken as the type of the whole, cease to 

 move onward and ascend. This operation is the reverse of that 

 which took place at the meeting (§ 210) near the belt between the 

 parallels of 30°-35°. 



213. This imaginary particle then, having ascended to the upper 

 The calm bait of rogions of the atmosphcre again, travels there coun- 

 Capricoin. |.g^, ^q |]^q south-cast tradcs, until it meets, near the 

 calm belt of Capricorn, another particle from the south pole ; here 

 there is a descent as before (§ 210) ; it then (§ 211) flov\^s on 

 towards the south pole as a surface wind from the north-west. 



214. Entering the polar regions obliquely, it is pressed upon by 

 The polar calms and similar particlcs flowdug in oblique crn'rents across 

 the return current, evcij meridian ; and here again is a calm place or 

 node ; for, as our imaginary particle approaches the parallels near 

 the polar calms more and more obliquely, it, with all the rest, is 

 v/hirled about the pole in a continued circular gale ; finally, reach- 

 ing the vortex of the calm place, it is carried upward to the regions 

 above, whence it commences again its flow to the north as an 

 upper current, as far as the calm belt of Capricorn ; here it en- 

 comiters (§ 213) its fellow from the north (§ 207) ; they stop, 

 descend, and flow out as surface currents (§ 210), the one with 

 which the imagination is travelling, to the equatorial calm as the 

 south-east trade-wind; here (§ 212) it ascends, travelling thence 

 to the calm belt of Cancer as an upper cmTcnt comiter to the north- 

 east trades. Here (§ 210 and 209) it ceases to be an upper cur- 

 rent, but, descending (§ 210), travels on with the south-west 

 passage-winds towards the pole. 



215. Now the course we have imagined an atom of air to take, as 

 n-agrnm of the illustratcd by the " diagram of the winds," (Plate I.) 

 '^"''''^- is this : an ascent in a place of calms about the north 

 pole, as at Y P ; an efllux thence as an upper current, A B C, 

 imtil it meets E S (also an upper current) over the calms of 

 Cancer. Here there is supposed to be a descent as shown by the 

 arrows, C D, S T. This current, A B C D, from the pole, now 

 becomes the north-east trade-wind, D E, on the surface, until it 



