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 box Junk box Junk box is a term used by amateur radio operators (hams) to describe a collection of spare parts and old equipment kept to assist in building and repairing their station. Typical items found in a junk box are electronic components such as resistors and capacitors as well as small parts such as screws, nuts and bolts. A junk box may also contain surplus, cast off or used electronic gear. Radio amateurs who construct their own equipment, known as homebrewers, often have large or well stocked junk boxes. According to some hams, a well-stocked junk box is a requirement