IN PERILS BY SEA. 
143 
examples of true heroism and patriotic devotion 
to duty. 
The dangers which then had to be encountered 
were rendered more formidable by the absence of 
any correct chart or map, either of the coasts of 
Africa or Asia, or the numerous currents—such 
as those of the Mozambique Channel and Agul¬ 
has—which have a great influence, and must 
always be taken into account in approaching 
these seas. 
The most useful addition to modern atlases is 
the Wind map , upon which is shown with almost 
unerring accuracy the direction and force of the 
various atmospheric currents, and by the use of 
which the seaman of to-day can find in any 
quarter of the world the prevailing wind, and 
avail himself of its help to go a straight course 
to his destination, without having to wait, as 
formerly, till he found it, or drift aimlessly about 
the ocean seeking for it, or perhaps beating up 
against an adverse blast, whilst, only a few 
leagues off, had he known it, he could have 
found a “ trade” that would have carried him 
literally on its wings to “ the haven where he 
would be.” 
This wider knowledge of the winds and cur¬ 
rents has already considerably shortened the 
passage to India and Australia, and has very 
much reduced the risk of the Eastern passage. 
