130 THE PHYSICAL GEOGRAPHY OF THE SEA. 



With regard to this outer and under current, we have observa- 

 tions telKng of its existence as long ago as 1712. 



'' In the year 1712," says Dr. Hudson, in a paper conaniunicated 

 to the Philosophical Society in 1724, " Monsieur du L'Aigle, that 

 fortunate and generous commander of the privateer called the 

 Phoenix, of Marseilles, giving chase near Ceuta Point to a Dutch 

 ship bound to Holland, came up with her in the middle of the Gut 

 between TarifFa and Tangier, and there gave her one broadside, 

 which directly sunk her, all her men being saved by Monsieur du 

 L'Aigle ; and a few days after, the Dutch ship, with her cargo of 

 brandy and oil, arose on the shore near Tangier, which is at least 

 four leagues to the westward of the place w^here she sunk, and di- 

 rectly against the strength of the current, which has persuaded 

 many men that there is a recurrency in the deep water in the 

 middle of the Gut that sets outward to the grand ocean, which this 

 accident very much demonstrates ; and, possibly, a great part of 

 the w^ater wdiich runs into the Straits returns that way, and along 

 the two coasts before mentioned ; otherwise, this ship must, of 

 course, have been driven toward Ceuta, and so upward. The 

 water in the Gut must be very deep ; several of the commanders 

 of our ships of w^ar having attempted to sound it with the longest 

 lines they could contrive, but could never find any bottom." 



In 1828, Dr. Wollaston, in a paper before the Philosophical So- 

 ciety, stated that he found the specific gravity of a specimen of 

 sea water, from a depth of six hundred and seventy fathoms, fifty 

 miles within the Straits, to have a " density exceeding that of dis- 



!Mediterranean appears to have been a vexed question among the navigators and phi- 

 losophers even of those times. Dr. Smith alludes to several hypotheses which had 

 been invented to solve these phenomena, such as subterraneous vents, cavities, exha- 

 lation by the sun's beams, See, and then offers his conjecture, which, in his own 

 words, is, "that there is an under current, by vv'hich as great a quantity of water is 

 carried out as comes flowing in. To confirm which, besides what I have said above 

 about the difference of tides in the ofling and at the shore in the Downs, which ne- 

 cessarily supposes an under current, I shall present you with an instance of the like 

 nature in the Baltic Sound, as I received it from an able seaman, who was at the 

 making of the trial. He told me that, being there in one of the king's frigates, they 

 went with their pinnace into the mid stream, and were carried violently by the cur- 

 rent ; that, soon after this, they sunk a bucket with a heavy cannon ball to a certain 

 depth of v/ater, which gave a check to the boat's motion ; and, sinking it still lower 

 and lower, the boat was driven ahead to the windward against the upper current : 

 the current alofl, as he added, not being over four or five fathoms deep, and that the 

 lower the bucket was let fall, they found the under current the stronger." 



