For a long period the rig of ancient ships was of the simplest kind—a single large square sail on the mainmast being the chief means of propulsion. In the case of large vessels there was a sort of square sail on a short mast at the stern, and a similar one at the bow; but these would be of more use in steering than in propelling. The Romans appear to have had a small triangular sail, like the Greek letter Delta (Δ), which bore the name of suppara, from its supposed resemblance to a woman’s shift;[42] but such a sail could only have been used in fair weather.
Undergirders.
“Undergirding” a ship, as mentioned by St. Luke, is rarely practised at the present day; but implements for that purpose—probably stream cables or hempen hawsers—would seem certainly to have been part of the occasional outfit of ancient vessels. They are mentioned as having been kept in store in the Athenian arsenals, and to have been served out for voyages known to be of unusual danger.[43]
Anchors and cables.
The use of anchors was early understood, but, in Homer’s time, they were simply large stones attached by ropes to the prow.[44] In after-times, much attention seems to have been paid to their construction,[45] and ships often carried several (as St. Paul’s, which had four[46]). A cork float marked where the anchor was sunken;[47] and chain cables were sometimes used, as is noticed by Arrian in his account of the siege of Tyre by Alexander.[48] In St. Paul’s case, the fact that the ship was able to anchor by the stern probably saved the lives of those on board, as otherwise she might have driven broadside on the rocks.
Decks.
But though, as we have stated, the small early coasting vessels may have had no decks, the large grain-carrying ships, which performed the voyages between Alexandria and Italy, were unquestionably fully decked. In the so-called “ship of Theseus,”[49] there is a complete deck, and also what would seem to be a skylight; nor need we doubt that, in the largest and best-fitted ships, there was adequate accommodation for both men and officers. The great ships constructed by Ptolemy Philopater and Hiero were (as we shall see hereafter) rather “show-ships,” and cannot be considered as representing the usual type of even the most sumptuous of ancient merchant vessels.
Nautical instruments.
The skilled mariners of ancient days determined their latitude by means still in use, but their instruments were very inferior. The gnomon, in some form or other, was their most common instrument for measuring the length of the sun’s shadow at noon on different days and in different places. We know from Herodotus,[50] that this instrument was of great antiquity—indeed, he ascribes the invention of it to the Babylonians; but the report of Arrian to the Emperor Hadrian[51] of his shipwreck implies that there were other instruments besides this on board. Pytheas, the first known navigator of the North Sea, is said to have determined the summer solstice at Marseilles by observing the proportion of the shadow of the gnomon.[52] Further, Eratosthenes drew a parallel of latitude through Gibraltar, Rhodes, and Lycia to India; while Hipparchus made the first map, on the principle of “Mercator’s Projection,” by transferring the celestial latitudes and longitudes to the terrestrial globe. On the other hand, Ptolemy erred so far in his calculation of the longitude, that he placed China 60° nearer Europe than it really is, and thus led Columbus to fancy the distance he had to traverse to the New World was just so much less. It must not, however, be forgotten that Aristotle, centuries before him, when reasoning from the assumed sphericity of the earth, was really the first to point out that the west coast of Spain was the fittest point of departure for India.
The latitudes were reckoned in stadia from the Equator to Syracuse, the stadium being about two hundred and one yards and one foot. The determination of the longitude was, however, a far more difficult problem; as the only phenomena whereby men could readily determine the distance between any two places, viz. eclipses of the moon, would have been of no practical value in calculating a ship’s position at sea; moreover, it would not be easy to secure certainty in such observations, nor could they easily be repeated. Hence the ancients were led to depend either on actual survey, or on the vague information obtainable from the reckonings of sailors, or on the itineraries of travellers. We need not, therefore, be surprised when we see how Ptolemy and the greatest of ancient geographers have erred, owing to the impossibility of fixing with even tolerable accuracy the longitudes of different places. It is likely that their practice of constantly landing might have in some degree supplied their deficiency in this particular; but we have now no record of any astronomical observations which were made at sea, by even the most skilful of ancient navigators. A sort of dead-reckoning—an observation of the position of the sun during the day, or of certain stars during night—was the haphazard mode by which their positions at sea were chiefly ascertained. If they had been accustomed to steer a direct course instead of following the coast line, or if they had been acquainted with the properties of the compass, or of any instrument by which the bearings of the different headlands could have been determined, they might, having found their latitude, have depended, as mariners in modern times have been often obliged to depend, with some confidence upon their dead-reckoning. The wonder is that they should ever have ceased to hug the land, and that they really ventured on the long voyages they unquestionably accomplished.