INTRODUCTION. vii 



the flight and length of the arrows designated the velocity and set 

 of the currents. 



XI. Thus the eye was successfully addressed ; for, by a mere 

 glance at the chart, the navigator saw in a moment from what 

 quarter he might expect to find the wind in any part of the sea to 

 prevail for any month ; and he thus had to guide him across the 

 pathless ocean, not theory or conjecture, nor the faint glimmerings 

 of any one man's experience, but the entire blaze and full flood of 

 light which the observations of all the navigators that had preceded 

 him could shed. 



XII. Thus, while the young ship-master, with these charts be- 

 fore him, would be immediately lifted up and placed on a footing 

 with the oldest sea-captains in this respect, the aged might see in 

 these charts also the voyages made in their young days spread out 

 before them. There, on the chart, was the ship's name, her track, 

 the year ; and, by the color and fashion of the line (§ IX.), the 

 month might be told. There, on that day, in that latitude and 

 longitude, these charts would remind the old sailor that he had en- 

 countered a terrible gale of wind ; there, that he had been beset 

 with calms ; how here, with fair winds and a smooth sea, he had 

 made a glorious run. Here, he had first encountered the trades ; 

 and there, lost them. At this place, he had met with a '^ hawsing 

 current." Here, the winds were squally with rain ; and there, it 

 was he had been beset with fogs ; here, with thunder-storms. All 

 this was seen on paper, and so represented as to recall the reality 

 vividly to mind. 



XIII. Such a chart could not fail to commend itself to intelli- 

 gent ship-masters, and such a chart was constructed for them. 

 They took it to sea, they tried it, and to their surprise and delight 

 they found that, with the knowledge it afforded, the remote corners 

 of the earth were brought closer together, in some instances, by 

 many days' sail. The passage hence to the equator alone was 

 shortened ten days. Before the commencement of this undertak- 

 ing, the average passage to California was 183 days ; but with 

 these charts for their guide, navigators have reduced that average, 

 and brought it down to 135 days. 



XIV. Between England and Australia, the average time going, 

 without these charts, is ascertained to be 124 days, and coming, 



