TIDES AND OCEANIC HIGHWAYS. 365 



currents is not invariable, but is much accelerated or retarded by the prevalence of hard 

 gales, the navigator sailing with or against them has to take this element into the 

 account, in order to be sure of his place. In proceeding from the American coast to 

 Bermuda, Captain Hall found that an unusual increase in the rate of the gulf stream 

 had carried him so far beyond his mark, that when from his reckoning, the weather 

 having prevented observations for the longitude, he supposed himself about forty miles 

 on the western side of the island, and was therefore beating to the eastward, he was 

 actually about the same distance on the eastern side, and had to sail westward to gain his 

 port. By not making due allowance for the force of the current that sweeps round the 

 Cape of Good Hope from the Pacific, navigators proceeding to India have often fancied 

 themselves east of the Cape when they have been still west, and have been driven ashore 

 on the African coast, which, according to their reckoning, lay behind them. A similar 

 cause has led to many a disastrous shipwreck on the Senegal coast, upon which a branch 

 current from the gulf stream rushes, and upon the savage shores of the Great Desert, it 

 has been the fate of many a gallant crew, either to perish of hunger or to be sold into 

 slavery. A more accurate acquaintance with oceanic regions, and the accomplished 

 nautical education of commanders, have diminished such accidents in recent times. Still, 

 besides the great sea-streams, there are an immense number of offsets from them, some 

 of which are only occasional currents, and others have not been noticed, which may 

 deceive the most skilful commander, and hurry his vessel ashore, when his reckoning 

 gives him a considerable distance from it. This misfortune happened to the fine frigate 

 the Challenger, in the year 1835, which struck upon the south coast of Chili, owing to 

 the action of an unusual and unexpected current, against which it was impossible to 

 guard. At eight o'clock in the evening there was a careful examination of the ship's 

 place upon the charts. At nine, the weather was hazy, the wind moderate, the water 

 smooth, the stars occasionally appearing overhead, and an expected moon at midnight 

 promised a fine and quiet night to the crew. At a quarter to ten the breakers were 

 seen, and immediately the ship dashed upon the rocks along the beach, became a complete 

 wreck, the officers and men reaching the shore with difficulty. 



The existence of under-currents, running in a direction opposite to the flow of the 

 surface stratum, has been surmised in various places, but chiefly owing to circumstances 



Sinope, on the Black Sea. 



