To determine the day on which Cæsar landed, it is necessary, in the first place, to know to what part the Roman fleet was carried during the night. It is evident, first, that it was borne towards the north-east by the current of the rising tide or flux, for otherwise we could not understand how Cæsar, at sunrise, could have perceived Britain on his left. We may add that it wandered from its way till it came to the latitude of the Northern Sea, which is situated to the east of Deal, and at about ten maritime miles from the coast. (_See Plate 14._) In fact, according to the text, the fleet took advantage of the current contrary to that which had carried it away, and consequently of the reflux or current of the ebbing tide, to reach the coast. Now, we are obliged by this fact to conclude that it had been carried northward at least to the latitude of Deal; for, if it had only arrived to the south of that latitude, the reflux would necessarily have thrown it back into the Straits. Lastly, to cause the fleet by force of rowing and aided by the reflux to require eight hours to effect the last part of its passage to Deal, it must, according to the best information obtained from sailors, have been, at sunrise, ten miles from the coast. This being granted, it is evidently sufficient, for determining the day of landing, to resolve this question: on what day of the month of July in the year 700 the current of the descending tide began to be perceived _at sunrise, that is, towards four o’clock in the morning_, in the part of the sea at ten miles to the east of Deal? or otherwise, if we consider that the reflux begins there about four hours and a half after the hour of high tide at Dover,[417] what day of the month of July in the year 700 it was high tide at Dover towards half-past eleven o’clock at night? By following a train of reasoning similar to that which we applied to determine the day of Cæsar’s first landing in Britain, and remarking that the tides of the days preceding the full moon of the month of July, 700, which fell on the 21st, correspond to those of the days which preceded the full moon of the 26th of July, 1858, we find that it was either fifteen days or one day before the 21st of July of the year 700, that is, the 6th or the 20th of July, that it was high tide at Dover towards half-past eleven at night. Cæsar, therefore, landed on the 7th or on the 21st of July. We adopt the second date, because, according to Cicero’s letter cited above, he received, before the 26th of July, at Rome news of his brother, which must have been of the 6th of the same month, as the couriers were twenty days on the road. In this letter Quintus announced his approaching departure for Britain.