PREHISTORIC NAVAL ARCHITECTURE. 621 



curviitiire of 5 inches in the. middle; the euds are thus liij^lier tluiu 

 the middle which, in connection with the j)romiueut stems, has a tend- 

 ency to increase the strengtli by ])lacing the greatest draft where the 

 shij) is the broadest. 



The ribs, seventeen in nnmber, are not fastened to the keel, but lie 

 free above it at eqnal distances of 3 feet. The beams rest on the top of 

 theknees, the height of which corresponds to the tenth external plank 

 and thns a solid basis is formed upon which the comparatively lighter 

 superstructure rests. From the beams frame timbers extend to the 

 height of the fourteenth strake, and further support is given to the 

 structure by short timbers placed between every alternate frame and 

 extending from the gunwale downward, and by similar supports 

 mortised into the beams and with their lower ends cut so as to straddle 

 the bottom timbers. 



The beams being wider than the ribs upon which they are fastened 

 and the frames of the superstrncture, a ledge is formed upon which the 

 cuds of the bottom l)oards rest; these consist of thin fir boards laid 

 edge to edge, each pair being bound together by a (crossbar nailed to 

 their underside Avith trenails; they are laid at right angles, but the 

 outer layers conform to the curv;iture of the shii). All the boards were 

 ornaiueuted with concentric circles or otlier patterns. 



The external covering consisted of sixteen x)lanks tightened with 

 cattle hair spun into three-stranded rope, Avhich process would indicate 

 that the caulking was done simultaneously with the laying of the 

 ])lanks. The planks vary in width from 7 to 9 inches, with a thickness 

 of three-fourth inches; exceptions to this exist in the tenth strake, the 

 thickness of which is 1^ inches, and the fourteenth, which is 1 inch 

 thick; the two top planks are one-luilf inch thick only. Additional 

 strength is thus given to those planks corresponding to the position of 

 tlu', beam and the ends of the short ribs. 



The ])hinking (Fig. l-J-S) wms s<M'Ur('d to the frame in the same manner 

 as observed in the Tune shi[>, Jiainely, the eiuls of all tlie phiuks were 

 cut tapering so as to closely tit the stem and sternposts, to whicli tiu'y 

 were imih'd witli iron s[)ikes; thebottoni ])huik was fastened totlie keel 

 with iron rivets, and trenails weie use<l to fasten the two top planks to 

 the frames. All intervening planking (Fig. 139), although fastened to 

 eaeli other with rivets, were tied to the fianies by means of withes made 

 from roots and i»assing through clanii)s that had been cut out of the 

 solid ])lank and corresponding holes in the ribs. 



The ribs tlius resting on the planks form, in connection with the 

 tliwarts, a solid body, stift'eniug tlie shij) towards the sides; in the 

 (iokstad ship the thwarts are the beams upon which tlie bottom (or 

 deck) boards rest; nor could they be absent in a ship of this size, be- 

 cause clinker-built ships have their principal strength in the outer 

 covering which is held in shape by the pressure against the well con- 



