12. The inspection of this table shows that it was the practice of the sixteenth century to send out fleets of ships of a very small size, that in the seventeenth one small ship was commissioned, and that the employment of two vessels has been the rule since; and this would have been still more evident, if the various Franklin expeditions had been included in the above table. In 1829 Sir John Ross started with a ship drawing eighteen feet, but changed afterwards to one drawing eight feet; and from eight to twelve feet is now the recognised draught in Polar ships. Large vessels require a numerous crew, and if they have not been built exclusively for the purpose of Polar exploration, their small economy of space prevents their being fitted out for more than two years and a half. In 1819 Parry’s ship, the large _Fury_, had, with a draught of eighteen feet, provisions for only two and a half years, whereas the _Victory_ (1829) of Ross with only seven feet draught had on board, besides stores for the same period, a steam-engine and coals for a thousand hours’ steaming. The Russian Novaya Zemlya navigators of this century have adopted vessels of a size which must be destructive of all comfort and convenience. These vessels are thirty or forty feet long, with a draught of five or six feet, and a crew of nine or ten men. But Arctic ships must have a crew above the ordinary strength and be provided with steam-power; so that, allowing for the necessary space for the quarters of the crew, for the engines and the coalbunkers, little room will be left for the stowage of stores. But this little should be reserved for well-chosen provisions stowed away so as to avoid all empty spaces, and secure the greatest amount of resistance to lateral pressure. The weakest parts of a ship are always the spaces left for air in the quarters of the men. A crew, which is exposed to threatening dangers from the ice, will never regret the strengthening of these void spaces by heavy horizontal tie-beams, removable when the ship is in the winter harbour, and so adjusted as not to impede communication. The mere suspension of heavy beams against the hull of a ship does not always answer the purpose of protection, since the pressure of the ice frequently drives away these protecting timbers. The practice, however, is not absolutely to be rejected.