Pontoon bridge in 638. The army of the Umayyad Caliphate built a pontoon bridge over the Bosporus in 717 during the Siege of Constantinople (717–718). The Carolingian army of Charlemagne constructed a portable pontoon bridge of anchored boats bound together and used it to cross the Danube during campaigns against the Avar Khaganate in the 790s. Charlemagne's army built two fortified pontoon bridges across the Elbe in 789 during a campaign against the Slavic Veleti. The German army of Otto the Great employed three pontoon bridges, made from pre-fabricated materials, to rapidly cross the Recknitz river at the Battle on the Raxa
Junk rig running rigging which pulls up the junk sail are: The running rigging which pulls down on the junk sail are: The running rigging that sets or trims the junk sail (controls the angle of attack relative to the direction of the wind) is the "sheet". On a traditional Chinese junk rig, the sail is controlled by "sheetlets"—small sheet lines running from the battens to blocks that in turn are on lines running through a "euphroe," a long piece of wood with holes in it. This helps maintain uniform tension in each panel of the sail. Western ship designers Tom Colvin,