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. [Sidenote: 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] [Sidenote: 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. [Sidenote: 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. [Sidenote: Nautical instruments.]