“We may add (continues our author), that the mean rate of Nearchus was no more than twenty-two and a half during his voyage; and less than thirty through the Persian Gulf. But we regard his rate as unusually low, for the reasons above stated[17].”
“It appears from Procopius (Vandal. lib. i. c. 12), that the fleet of Belisarius was sixteen days on its passage from Zante to Caucana in Sicily. The distance being three hundred and twenty geographic miles, gives twenty such miles per day, or about two hundred and fifty stadia. This must be regarded as the effect of oars generally; there being very little wind, or almost a continued calm.”
“Diodorus (lib. v. c. 2) says, that tin was carried across in four days from Britain to Gaul, where it was landed, and carried across the Rhone in thirty journies. From the descriptions and the circumstances altogether, it appears to have been embarked at St. Michael’s Mount in Cornwall, and landed near the other mount of the same name in France; perhaps at St. Maloes.”
“This would give a rate of about forty miles per day: but he says (Diodorus) that the western promontory of Britain is four days’ sail from the opposite continent.”
“It is conceived (Major Rennell continues) that the slow progress of the vessels of the ancients will be readily admitted; since in addition to so many other examples, we have the reports of Herodotus and Nearchus,—of the latter respecting the length of a day’s sail; of the former, as to the space actually sailed through in the course of a day, and remarked as an uncommon long run in those days: as also the time required to navigate the Red Sea and the Euxine, the latter of which appears to be reported from Herodotus’s own experience.”
“In effect none of these differ materially from the rest:—the mean rate of all, then, being so low as thirty-seven geographic miles, we are naturally led to inquire (continues the Major) why there should be so great a disproportion between the sailing of ancient and modern ships; since a day’s sail (of four-and-twenty hours) of a modern ship cannot be reckoned at less than three times that of the ancient ones?”
“Even the worst description of modern vessels of which we have any knowledge seems to be superior to the antient ones in respect of their daily progress. And therefore we suppose that some cause is to be looked for, besides that of dulness of sailing.”
“That this had a considerable share in the delay is evident, by the circumstance mentioned by Pliny (if we may depend upon the numbers), of the Roman Ships sailing no more than about forty-four geographical miles per day across to open sea between Arabia and India, in which we cannot suppose them to have absolutely stopped at night, as in their coasting voyages and in soundings.”
“We may reckon, at a medium, from thirteen to fourteen hours of daylight throughout the year in that parallel; so that three miles per hour for the daylight makes up the whole sum (bating three or four miles), which is a very slow rate of sailing before the brisk monsoon that prevails in that sea, and leaves little or nothing for the night; and although it is possible, and even probable, that they may have lain to during this interval, yet ten or eleven hours drift must amount to something. Hence we shall not lay so great a stress on this instance, being a solitary one of the kind, as on the others in the coasting navigation. In these it appears almost certain that the ordinary mode of sailing was confined to daylight; for without a compass, or a substitute for it, great danger must have been incurred in the night, when a small error in the angle of the course would be fatal. Lighthouses, on prominent parts of the coast, would doubtless direct them; but this could not be a general arrangement, and must have been confined to particular coasts only. Notwithstanding, sailing by night was doubtless practised occasionally, as in clear moonlight, or at other times when necessity pressed, or the nature of the shore (as at the mouths of the Tigris and Euphrates) prevented his coming to an anchor or landing. Sailing by night is also implied, when Scylax admits nights as well as days in his calculation of the distance between Carthage and the columns of Hercules; a navigation by no means intricate, and perhaps assisted by lighthouses or signal fires. It must also have been occasionally practised in the Euxine. (See Note to p. 678, article 6.)”
“In effect, then (Major Rennell continues), we must suppose a rate of sailing of only two and a half sea, or geographic, miles per hour, or less than three at the utmost. The cause must either have been the defective form of the ships’ hulls, or the faulty disposition of the cargo and ballast, which might not permit them to spread sail enough[18]. Certainly the sails of ancient ships are represented, on medals, as being remarkably small, and do not seem to be on a par in that respect even with Chinese junks, which, like the others, have generally lower masts only. If we reject the examples given by Herodotus on the Caspian Sea, and by Pliny in the open sea, as being out of rule, we have thirty-five (miles) only for the mean rate per day of the Grecian, Egyptian, Phœnician and Carthaginian ships, between the times of Darius, Hystaspes and Alexander, generally; and in which none rise above thirty-eight, or fall below thirty-two sea miles.”