The northern half of Bobington — or rather, the northern half of the most extraordinary model of Bobington ever constructed — sits on a reinforced table in the exhibition hall of the Historical Preservation Society on Grayling Street. It weighs, according to the men who carried it in on Tuesday morning, “approximately as much as a small piano and twice as much as a large dog.”

The southern half sits beside it on a parallel table, separated by a gap of nine inches that represents the River Ashwater in miniature.

Arthur Bayliss, the furniture restorer who cut the model at the river on Sunday 6 April, and his son James are now engaged in the more delicate work of putting it back together. By Thursday afternoon — day three of reassembly — eight of twelve mechanical connectors had been reattached. The clockwork tramline that runs from the model’s tiny Caldecott Square to its tiny Millgate was tested and ran smoothly for forty-five seconds before stopping, which Arthur attributed to “a speck of dust in the Midtown section.”

“It’s always Midtown,” said Oswin Faraday, who was watching from a folding chair with a cup of tea and an expression of anxious pride. “Midtown collects dust.”

Faraday — the retired tram conductor who spent eight years building this 14-by-9-foot mechanical model of the entire city in his Thornhill garage — has been a daily visitor since the halves arrived on Tuesday. He does not touch the model. He watches. Occasionally he points. Occasionally he winces. Once, when James reconnected the Docklands waterfront section and the aquarium pump sent a thin stream of water through the model’s tiny River Ashwater for the first time since the cut, Faraday stood up from his chair.

“She’s flowing,” he said, to no one in particular.

The model contains 2,340 buildings, 14 bridges, 6 clockwork tramlines, and 48 wired streetlamps. The streetlamps are the final challenge. Each is connected by fine copper wire to a single battery, and the wires were severed during the cut. James Bayliss has been resoldering them one at a time, working with a jeweller’s loupe and a soldering iron that looks, in his large hands, like a toothpick.

“Forty-eight lamps,” James said. “Sixteen done. Thirty-two to go. Some of the wires are thinner than a human hair. Mr Faraday’s wiring is…” He paused. “Idiosyncratic.”

“It works,” said Faraday.

Louisa Marchbank, chairwoman of the Historical Preservation Society, confirmed that the exhibition will open on schedule on Saturday 18 April. The model will be the centrepiece, displayed in the main hall under overhead lighting that Marchbank has commissioned specifically for the exhibition. Visitors will be able to walk around all four sides.

“People have been telephoning all week,” Marchbank said. “I have not advertised. I have not needed to.”

Constance Faraday, Oswin’s wife, visited on Wednesday. She inspected the exhibition hall, noted the quality of the lighting, and said: “It looks better here than it did in the garage.” She paused. “Don’t tell him I said that.”

The exhibition runs 18 April to 31 May. Free admission. Open daily except Monday.