APPENDIX. 
XXXV 
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 calcula- 
tion of the distance between Carthage and the columns of Hercules ; 
a navigation by no means intricate, and perhaps assisted by light- 
houses or signal fires. It must also have been occasionally prac- 
tised in the Euxine. (See Note to p. 678, article 6.) 
“ In effect, then (Major Rennell continues), we must suppose a rate 
