APPENDIX. xvii REMARKS ON THE NAVAL AFFAIRS OF THE ANCIENTS, AND THE RATES OF SAILING OF THEIR VESSELS AT DIFFERENT PERIODS.

The Greater Syrtis appears to have been at all times ill provided with ports and harbours, and may at the present day be considered to be wholly unprovided with any ; that is to say, with any which could be used as such by ships of modern construction. It will be observed that the whole line of coast laid down in the chart is, at the same time, very indifferently formed by nature to afford security to vessels of any description.

It was not, however, necessary that the ports of the ancients should possess wholly by nature those local advantages which are at the present day considered to be essential for affording protection ; and we find that many of them existed in places which must always have been unqualified by their position for affording the security required. In such places art was made to supply the deficiencies of nature, and harbours were built where none could otherwise have been obtained. The mode of constructing these artificial ports has been clearly defined by Vitruvius ; and as it may serve to explain what we have stated with respect to the present state of the ports of Ptolemeta and Aspis, we shall submit the passage in question as we have extracted it from Wilkins’s translation.

“ A spot was, if possible, selected, which had the advantage of some protection on one of its sides; and the want of a corresponding defence on the other side was supplied in the following manner : — rows of grooved beams were driven in the water, connected by oaken planks, and bound together by chains. The surface of the ground below the water was then levelled and consolidated by means of transtilli, and the space comprehended between the beams filled up with a composition of rough stone, and cement formed of sea-sand mixed with lime, in the proportion of two parts to one, which soon