A great obstacle presented itself at the outset. The aid of steam in the navigation of my ship, was necessary to render my enterprise safe and expeditious against the adverse circumstances which I was sure to meet. But steam vessels were adapted only to smooth water. Every attempt to employ them upon the ocean had been unsuccessful. I foresaw that I must have a vessel capable of encountering severe gales in a dense atmosphere, of being rapidly impelled against strong currents, both of wind and water, and of surmounting, without harm, the impetuous tides, and resisting the violent winds to be expected in the polar seas. Moreover, she must be of such strength as to sustain the shock of floating ice, or of taking the ground; and of such capacity as to contain fuel and provisions for at least fifty men for three years, with apartments from which the external air could be excluded, and which might be artificially warmed during the rigours of a polar winter. But he whose soul is fired with the true spirit of discovery, is not to be dismayed. I saw the end, and instantly began to use the means of attaining it. I caused a steam vessel of 400 tons to be constructed with double frames; the timbers being inclined from a perpendicular about 45 degrees; so that the outer set crossed the others at right angles. The timbers were let into each other to the depth of three inches, and were secured by powerful bolts. This structure of massive grating was incalculably firmer than the frame of a ship could possibly be made upon the ordinary plan. The bottom was covered with four inch plank, over which, after they were fastened and caulked, a layer of three inch plank was put on; and the whole was sheathed with copper of unusual thickness.