834 THE PHYSICAL GEOGRAPHY OF THE SEA. 



CHAPTER XY. 



§ 621-680. — SEA ROUTES, CALM BELTS, AND VARIABLE WINDS. 



621. Plate YIII., so far as the winds are concerned, is supple- 

 practicai results of mental to Platc I. Tlic former shows the monsoon 

 sea. regions, and indicates the prevailing direction of the 

 winds in every part of the ocean ; the latter indicates it generally 

 for any latitude, without regard to any particular sea. Plate VIII. 

 also exhibits the principal routes across the ocean. This plate in- 

 dicates the great practical results of all the labor connected with 

 this vast system of research ; its aim is the improvement of navi- 

 gation ; its end, the shortening of voyages. Other interests and 

 other objects, nay, the great cause of human knowledge, have been 

 promoted by it ; but the advancement that has been given to these 

 dp not, in this utilitarian age, and in the mind of people so emi- 

 nently practical as mariners are, stand out in a relief half so grand 

 and imposing as do those achievements by which the distant isles 

 and marts of the sea have, for the convenience of commerce, been 

 lifted up, as it were, and brought closer together by many days' 

 sail. 



622. So to shape the course on voyages as to make the most of 

 Time-tables. thc wiuds and currcuts at sea is the perfection of 



the navigator's art. How the winds blow and the currents flow 

 along this route or that, is no longer matter of opinion or subject 

 of speculation, but it is a matter of certainty determined by actual 

 observation. Their direction has been determined for months and 

 for seasons, along many of the principal routes, with all the accu- 

 racy of which results depending on the doctrine of chances are ca- 

 pable ; and flirther, these results are so certain that there is no lon- 

 ger any room for the mariner to be in doubt as to the best route. 

 AVhen a navigator undertakes a voyage now, he does it with the 

 lights of experience to guide him. The winds and the weather 

 daily encountered by hundreds who have sailed on the same vo}^- 

 age before him, and "the distance made good" by each one from 

 day to day, have been tabulated in a work called Sailing Direc- 



