OCEAN CURRENTS 139 



The normal conditions of cold and heat and wind soon 

 resume their sway, and the beneficent average circula- 

 tion is maintained from age to age. Nevertheless, in 

 these days of rapid transit, when the passage of a 

 steamship between port and port is reckoned by hours, 

 it remains one of the most important problems con- 

 fronting the navigator to allow for the incidence of 

 the current upon his vessel, for it must be re- 

 membered that, whatever the power and consequent 

 speed of a ship may be, the effect of a current upon 

 her remains the same. It is the movement of the 

 whole body of water in which she floats, and although 

 her speed may be twenty miles an hour through the 

 water, if there be a current of half a mile an hour 

 against her, and it is not known, she will be twelve 

 miles astern of the position she ought to be by her 

 course and distance run at the end of the day. And 

 a corresponding alteration in her position will take 

 place, no matter what the angle may be in which the 

 current strikes the ship. As long as the heavenly 

 bodies are visible and the ship is a good distance from 

 land, it does not matter, her position can be continually 

 verified. But when near land and unable to consult 

 those faithful celestial guides by reason of their being 

 hidden behind a pall of clouds, the sudden incidence 

 of a current previously unknown may mean a terrible 

 disaster, and one too that the navigator is powerless to 

 foresee and consequently guard against. Of course, if 

 the commander of a swift mail steamer, let us say, 

 were empowered, in the absence of celestial observa- 

 tion, to slow down as well as take a series of soundings 

 by the patent sounding machine, the danger of running 

 ashore would be minimized ; but even then on certain 



