130 
THE PHYSICAL GEOGRAPHY OF THE SEA. 
With regard to this outer and under current, we have observa- 
tions teUing- of its existence as long ago as 1712. 
" In the year 1712," says Dr. Hudson, in a paper communicated 
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 where 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, pos&ibly, a great part of 
the water which runs into the Straits returns thiat 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 war having attempted to sound it with the longest 
lines they could contrive, but could never find any bottom," 
In 1828, Dr. WoUaston, 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, &c., and then olfers his conjecture, which, in his own 
words, is, " that there is an under current, by which 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 offing and at the shore in the Downs, which ne- 
cessarily supposes an under current, I shaU 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 water, 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 aloft, 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." 
