The Airship of Topal
The chief intellectual project of Ulumbra from the closing of the Elven Wars onward had been the crossing of the sundered seas. The currents that had risen between Auridon and the mainland after Mount Ator admitted no reliable navigation, and the question of how to reach Tamriel by some other means occupied the scholars of Falas for the whole of the Merethic Era. Generations of work yielded little. The records of Ulumbra preserve the names of perhaps a dozen attempts, all of them lost at sea or abandoned before launch.
Around the year 3E3500 a Falas-born explorer named Topal, who would later be remembered as Topal the Pilot, perfected a working model of an airship. No record of its construction survives. The only contemporary source for Topal's voyages is the Udhendra Nibenu, the Father of the Niben, an Altmeri epic preserved only in fragments, and the surviving verses describe the journeys rather than the craft. What can be said is that the airship flew, that it was capable of long crossings, and that it did what the fleets of Ulumbra had failed to do.
In his earliest test flights Topal claimed, in his own verses, to have reached even the mainland of Tamriel. Whether the claim is to be taken at face value is a matter on which the surviving fragments are not in agreement with themselves: one verse describes the verdant hills of a far coast, another places Topal back over Auridon within hours of his departure. The two cannot easily be reconciled. The chroniclers of Falas appear to have believed him in his lifetime, and the airship was treated from that point onward as a proven instrument.
The Altmeri Exodus
The Altmer of Auridon did not need to be persuaded twice. For nearly the whole of the Merethic Era they had lived as exiles in their own homeland, severed from Summerset and from the wider world, and the airship offered the first reliable means of leaving. Within two generations of Topal's first crossings the population of Ulumbra was substantially gone. Most returned to Summerset and a smaller number went on to mainland Tamriel.
Topal himself did not go with them. With a chosen company, the number of whom is not recorded, he flew his airship not toward Summerset and not toward the mainland but upward, toward the moon Seconda. The records of Falas end at his departure. Whether he reached the moon, what he found there, and what became of him and his company are questions the surviving sources do not answer and cannot answer. The Udhendra Nibenu breaks off before the voyage.
In every century since, in Auridon and on the mainland and in Summerset, watchers have reported sightings of an airship moving against the night sky. The descriptions vary wildly. Some place the craft against the face of Seconda itself, others have it pass low over rooftops in a silence that no machine of the sky should keep. A smaller number of claimants, scattered across the eras, have insisted that Topal spoke to them directly, gave them messages, and asked of them things they would not afterwards repeat. The chroniclers of every age have dismissed the reports as the work of dreamers and frauds, and have continued to dismiss them, and the reports have continued to be made.