Difference between revisions of "Fourth Bridge"

The ''[[Fourth Bridge]]'' is [[Roshar]]'s first airship, which uses hundreds of conjoiner [[fabrial]]s to move through the air. ItNamed after [[Bridge Four]], it was built in the first year of the [[ShatteredTrue PlainsDesolation]],s by a team of [[ardent]]s and namedengineers afterled by [[BridgeNavani FourKholin]].{{book ref|sa4|3}}

The ''Fourth Bridge'' is a rectangular, wooden box; a hundred feet long, sixty feet wide, and about forty feet high, with three decks within. Fans are built into the back to increase speed, though for now, the difference is minimal. At full speed, differencethe theyship providetravels isat minimalroughly five knots.{{book ref|sa4|3}}

The back half of the upper deck is covered by a semi-round roof, while the front half is open to the -air, and surrounded by a railing. [[Bridge Four]]'s original bridge is embedded into the floor; some of the [[Windrunners]] have a habit of kneeling down and touching it before taking off. A command station, composed of several tables, is typiacallytypically placed in the sheltered partsection, though in some cases, it might be moved to the front. The furniture is bolted down.{{book ref|sa4|3}}{{file ref|Navani's Notebook - The Fourth Bridge.jpg|text=The Fourth Bridge}}

The lower decks serve as the hold. ItThe bottom one has widea broad door that open, allowingallows large amounts of people to come in and out at once. It functions akin to a drawbridge; normally, it isforms part of thea wall, and can be lowered and raised by ropes to open and close it. While sparsely-furnished, the holds can accomodate several hundred people.{{book ref|sa4|3}} There are numbers painted on thetheir walls, dividing the holdthem into a number of sections.{{book ref|sa4|6}}{{file ref|Navani's Notebook - The Fourth Bridge.jpg|text=The Fourth Bridge}}

The airship doesn't so much fly as it floatsis held in the air by [[fabrial]]s. There are hundreds of gemstones forming a lattice of masive Cojoiner [[fabrial]]sconjoiners embedded into the ship. They are connected to a pair of "dummy ships". One of the dummies is hanging off the side of the [[Urithiru]] plateau; the other is builtstands on the [[Shattered Plains]].{{book ref|sa4|15}}{{book ref|sa4|19}} The airship is steered from those two lattices; the ''Fourth Bridge'' communicates its needs to them through [[spanreed]]s. As they cannot be used for long periods of time due to movement, the scribes use them by turning them on and off, creating a code of blinks.{{book ref|sa4|3}}

The cojoinerconjoiner fabrials are isolated using [[aluminum]] so that only certain planes of movement are transferred between the paired gem halves. The Urithiru structure can only convey vertical motion; the Shattered Plains lattice can only transfer horizontal motion. The former is lowered to raise the airship, while the latter is moved around to make it fly and turn in any direction.{{book ref|sa4|19}}{{book ref|sa4|3}} To allow the ship to continue moving when the space for the lattices runs out, an additional aluminum mechanism is used to reverse the motion while the gemstones are temporarily unhooked.{{book ref|sa4|3}}

The entire structure requires significant manpower to function properly. In Urithiru, hundreds of people operate the winches that raise and lower the vertical lattice; on the Plains, squads of [[chull]]s are used to move the ship horizontally. The entire''Fourth structureBridge'' requires hundreds of gemstones to be perpetually infused with [[Stormlight]].{{book ref|sa4|3}} Fans have been installed to ease the load on the horizontal fabrials, but as of right now, they are barely functioning. There are also weight concerns, as adding too much mass to the existing structure might cause the gemstones to crack.{{book ref|sa4|6}}

{{image|Ship Designs.jpg|side=right|width=200px250px|Navani's early airship designs}}

[[Navani Kholin]] began conducting her first tests a few months after arriving aton the [[Shattered Plains]], in the last year of the [[War of Reckoning]]. The first conductedearliest experiment was comprised of a tall tower, with its top and the column abuilt as separate pieces, and a paired circular platform with crenellations. After infusing the embedded fabrials with Stormlight, when the pillar was rolled away, the top of the tower remained floating. As the top was pulled down, the platform rose into the air, creating an archer parapet unassailable to anyone standing below. ItWhile seemsthis thatwas already useful, even back then, there were plans to do more with the technology.{{book ref|sa2|35}}

Over time, Navani and her [[ardent]]s improved the platforms even as they began planning for more ambitious projects. Shortly after the [[True Desolation]] began, Navani beganstarted planning fordesigning proper airships; her initial designssketches were more ship-like, with massive sails attached upside-down to the bottom of the hull.{{book ref|sa3|50}} However, proper construction began only after the [[Battle of Thaylen Field]], as Navani threw herself into work following the death of her son, [[Elhokar]].{{book ref|sa4|3}} A few months after the battle, the Alethi built a pair of massive platforms off the sides of the [[Urithiru]] plateau as their early experiments. By then, rumours of what they were planning began to spread covertly among the high-ranking members of the coalition.{{book ref|sa3.5|2}}

As the twin platforms were being constructed, the ship ''[[Wandersail (1174 ship)|Wandersail]]'' set out to explore [[Aimia]]. As a favor to the expedition's leader, [[Rysn Ftori]], Navani sent along [[Rushu]], an ardent specializing in new fabrial designs.{{book ref|sa3.5|2}} Rushu attempted to make Rysn's chair float; however, the fact that the cojoinerconjoiner fabrials had to repeat the exact motion -- or the reverse of the exact motion -- of each other meant that the applications were severely limited.{{book ref|sa3.5|5}}

A breakthrough came from [[Huio]], one of the [[Herdazian]] [[Windrunners]] assigned to assist the expedition. ToAn sateamateur hisfabrial curiosityscholar, Huio disassembled one of Rushu's spanreeds and began experimenting on the gemstone with [[aluminum]]. After he put the spanreed back together, it began to behave oddly, transferring the movement of its cojoinedconjoined twin in an odd, jittery way. Realizing this would be a problem that couldn't be hidden, Huio and the other Windrunner on board, [[Lopen]], brought the broken spanreed to Rushu.{{book ref|sa3.5|7}} Upon examining it and experimenting further on Rysn's chair, Rushu realized that Huio managedaccidentally to useused aluminum to isolate the spanreed's planes of motion, so that only movement in specific directions was transferred between the two. This allowed for athe creation of a floating chair that could move freely by being pushed around.{{book ref|sa3.5|9}}

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