TRADE WINDS 



5856 



TRAGACANTH 



gion causes the air in the torrid zone to become 

 rarer and lighter, and consequently there is an 

 upward current into the higher atmosphere. 

 The surface currents from cooler regions north 

 and south, which flow into the equatorial belt 

 to take the place of the ascending currents of 

 warm air, form the trade winds. The fact that 

 they blow obliquely instead of directly north 

 and south is due to the rotation of the earth 

 on its axis. This movement turns them from 

 a straight course and makes them easterly 

 winds. The belt between the two sets of trade 

 winds is a region of calms, in which sailing 

 vessels in former days sometimes drifted for 

 weeks. The trade-wind zone itself shifts north 



TRAFALGAR, trafalgahr' ijn England, tra 

 fal'gahr), a low and sandy cape on the south- 

 west coast of Spain at the entrance to the 

 Strait of Gibraltar. It was off this cape on 

 October 21, 1845, that the famous battle was 

 fought in which Lord Nelson lost his life (see 

 page 4114). Although outnumbered by the 

 combined French and Spanish fleets under Vil- 

 leneuve and Gravina, the superior skill and con- 

 fidence of the British secured a decisive victory, 

 the French and Spanish losing nineteen out of 

 twenty-four ships. It was on this occasion that 

 Nelson signaled to his fleet, "England expects 

 every man this day to do his duty." The battle, 

 although a brilliant victory, ended in gloom, 



LOCATION AND DIRECTIONS OF THE TRADE WINDS 



and south with the seasons, reaching its north- 

 ern limit in September and its southern limit 

 in March. 



On land areas the trades have considerable 

 effect on rainfall. When they blow over low- 

 lands they take up moisture present in the at- 

 mosphere and create barren regions, as in the 

 case of the Great Sahara and the Central 

 Australian deserts. When they blow against 

 mountain ranges they are forced upward, and 

 the air on rising is cooled. This causes the 

 moisture to be condensed and rain to fall. 

 The northeast trades, for example, cause the 

 heavy rainfall on the eastern slopes of the 

 Andes and of the Mexican and Central Ameri- 

 can highlands. 



See WIND, for diagram of the circulatory sys- 

 tems of the world, and for list of other winds 

 with which th^e trades may be compared in their 

 cause and effect. 



for Nelson was mortally wounded in the hour 

 of his greatest triumph. 



Trafalgar since Nelson's time has been the 

 name of one of the most important squares in 

 London. On the north side of the square is the 

 National -Gallery, on the east the Strand and 

 Saint Martin's Church, on the south Whitehall, 

 the Horse Guards and the War Office, to the west 

 is the Hay market, with His Majesty's Theater 

 and Waterloo Place. In the square, guarded 

 by Landseer's lions of Britain, rises the monu- 

 ment to Nelson, the national naval hero. 



TRAGACANTH, trag'a kanth, a gummy sub- 

 stance yielded by the stems of various thorny 

 shrubs found in Asia Minor, Persia and Syria. 

 These shrubs belong to the Astragalus genus of 

 the pea family. The gum exudes through fis- 

 sures or cuts in the bark, and is usually mar- 

 keted in the form of thin flakes. It is of a 

 dull white or yellowish color, translucent and 



