VOL. xm.] PHILOSOPHICAL TKANSACTIONS. 44 1 



noon, the tide ran the same way he sailed. 3. That a S. by E. moon makes 

 high-water on all that coast, the flood coming from the southward : hence it 

 will follow, that that day it was high-water there about 8 in the morning, and 

 consequently low-water about 2 ; therefore by 3 the tide of flood was well made 

 up, and it is plain that Caesar went with it ; and the flood setting to the north- 

 ward, shows that the open plain shore where he landed was to the northward 

 of the cliffs, and must be in the Downs; and this I take to be little less than 

 demonstration. A second argument is drawn from the wind with which he set 

 out on his second expedition, viz. S. W. as appears by the words leni Africo 

 profectus, with which the navigation of those times would hardly permit a ship 

 to sail nearer the wind than 8 points, or a N. W. course ; which would serve 

 indeed to go into the Downs, but would by no means fetch the Lowland to- 

 wards Dungeness, which is much about west from Calais, and not more than 

 W. N. W. from Boulogne, if it shall be said that that was the Portus Icius 

 from which Caesar set out. Whence I take it to be evident, that if Ceesar 

 was not bound more northerly than the South-Foreland, he could not have 

 thought the Africus or S. W. wind proper for his passage, which was then 

 intended for the place where he first landed the year before. 



Justly to determine which the Portus Icius was, I find no where sufiicient 

 grounds ; only Ptolemy calls the promontory of Calais-Cliffs by the name of 

 *I)cio> aa^ov, whence there is reason to conjecture, that the Portus Icius was very 

 near thereto, and that it was either Atnbleteuse on one side, or Calais on the 

 other. The same Ptolemy places TuToppUxov Ixivuov in the same latitude with the 

 JxioK axfov, but something more to the east ; which seems to refute those that 

 have supposed the ancient port of Gessoriacum to have been Boulogne, whereas 

 by Ptolemy's position, it must be either Dunkirk or Graveling ; but most likely 

 the former, both by the distance from the "imov oix^ov, being about 20 miles or 

 half a degree of longitude to the east, or a of the whole coast of Flanders, 

 which he makes but a degree and quarter from the Acron Icion to the mouth 

 of the Scheld, which he calls OstiaTabudae: as also because that Pliny, 1.4. c. l6, 

 speaking of Gessoriacum, says the Proximus Trajectus into Britain, from thence 

 is 50 miles, which is too much, unless Gessoriacum were something more 

 easterly than Calais : Dion Cassius makes the distance between France and 

 Britain 450 stadia, or 56 miles, and says likewise it is the nearest, to cxivrofAurxrov. 

 But this is in part amended by the explication given in the Itinerary of Anto- 

 ninus, where the space between Gessoriacum and Rutupium is said to be 450 

 stadia, for this was the ordinary passage of the Romans into Britain, Rutupium 

 being more northerly, and Gessoriacum more easterly, than the termini of 

 Caesar's voyage, and consequently the distance greater than 30 miles, which 



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