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I made it, during the years I was an officer in that 
part of the world, (lixteen of which were employed 
in Gibraltar) part of my application to account, as. 
well as 1 could, for the difficulty of the navigation of: 
the ffrait ; as all'o the philofophy of it, with lefpedl 
to the furplus waters, fuppofed from the great inlets, 
and no apparent outlet. _ 
In order to which, the firff objedt prefenting ltfelf 
is the tides which came neceffarily under my no- 
tice, from one of the fervices, belides Other ciuties, I 
was engaged in ; namely, the forming an inunda- 
tion on the land fide of the garrifon ; the excavation 
of which being to be carried out, and thrown into 
the bay, depended almoff entirely on the tides, to 
bring the flat boats near the fhore, to receive the 
earth ; which in a manner compelled me to that 
confideration, on which much depended the execution 
of the work, which held upwards of four years ; 
during which time, the tides were,, in the main, 
from two to four feet rife, regular as in other places, 
unlefs by powerful winds without, 1 mean from the 
ocean, or Mediterranean, accelerated or retarded, 
which would a little vary the rife of water. 
That a very ffrong tide, at the rate of fome knots, 
fets from the ffrait into and out of Gibraltar bay, from 
Cabrita and Europa points, is notorious. . 
That this dream out and in by Europa is, by my 
effimation, a mile or better wide, I have frequently 
oblerved. 
At the fame time the tide has been pouring into 
the bay, round Europa, I have remarked, both fiom 
the high fhore and in boat, another ffieam in t e 
offing, going the contrary way. 
