World of Wonder: National Museum of Scotland set to shine again

• Exhibits will include, above, a series of rare Charles Rennie Mackintosh lamps and a magnificent 1950 Formula 3 racing car, below

ON A DAY so bitterly cold you would be forgiven for thinking we're entering the next ice age, I'm seeking out the jawbones of a sperm whale in Granton. We're at Edinburgh's National Museum Collection Centre, one of three facilities in the capital that together (if you count every worm in every jar) house almost four million objects. But we're looking for one in particular. Past the steam locomotives and the hulking back end of an elephant, the lamp acquired from the advertising hall of the original Scotsman offices and an original Apple Macintosh computer, the Icelandic carved headboards and the box with "shark" scrawled on it, we arrive at the bone collection.

"We have a lot," says senior curator Stephen Jackson modestly, gesturing at the rows upon rows of bones – ribcages, spines and skulls that in the dark look like slumbering prehistoric giants. "Here we are," he announces as we arrive at the enormous teeth-studded jawbones laid out on the floor. "They were taken down in the 1930s and they've been kicking around in the basements ever since. Now, finally, they're going to be seen again."

This is thanks to the Window on the World. Next summer the National Museum, formerly known as the Royal Museum, will reopen after three years. Its showstopper, seen as soon as you walk into the iconic building or step into one of the glass lifts, will be an 18-metre tall, 13.5m wide wall, rising from the floor to the eaves, housing a cornucopia of objects carefully chosen from the vast collection. An appeal, entitled Wall of Wonders, to raise the final 1 million needed for the 46.4m project has just been launched.

"The Window on the World will be like a giant steel scaffold," explains Jackson. "It will hopefully become iconic for the building and for Scotland." Having led the project since its inception in 2003, Jackson's job has been to visit more than 40 curatorial staff across five departments, asking each curator to put forward objects for the Wall. From a longlist of 1750, a total of 829 were eventually selected.

"It was a bit like going shopping in the most weird and wonderful bazaar," he continues. Though he has worked for the Museum for 11 years, he ended up discovering entire rooms, never mind objects, that he had never seen before. "It shows how unique we are. We're like the British Museum, Science Museum and V&A all rolled into one. Natural sciences, world cultures, Scottish history, art, science, technology, engineering. It's all here."

Around half of the objects have never been seen in public before. From molluscs in jars to a 1908 quadruplet bicycle, a gyroplane to Fijian clubs, the world's largest specimen of sarcolite crystal to a girder from the 1877 Tay Rail Bridge, the objects range from very old (a 2.8 billion-year-old rock from Lewis) to brand new (a wind turbine), from vast to minuscule, and many tell fascinating stories about Scotland's history.

Perhaps none more so than the jawbones. In 1843 Edinburgh University asked the crew of a whaling ship to bring back a set from this mysterious sea creature. The London boat, the Woodlark, manned by a Scottish captain called William Hardie, returned with the jawbones from a sperm whale they killed in the Banda seas off Indonesia. On the long voyage home the sailors carved drawings on the bones telling the story of the hunt. This example of ivory carving, known as scrimshaw, is thought to be the largest of its kind in the world.

"These are very unusual," says Jackson as we bend down to examine the delicate drawings of the scene depicting the ship, the islands and the whale in the water. "Collectible scrimshaw is either made on teeth or sometimes bits of bone. In this period Scots were going to other parts of the world and hunting down whales for oil. They basically threw spears at the whale, killing it bit by bit. It's terribly gory, not something to be proud of now."

Gruesome history aside, what's so extraordinary about this specimen is that the nation has never seen the scrimshaw before. "You can see by these boltholes that they must have been mounted so the scrimshaw was concealed and the public would never get to see it," Jackson explains. "It would have seemed like spray paint to them, graffiti."

In the engineering store, Chris Cockburn, engineering and technology conservator, talks us through the tallest object on the Wall. A railway signal gantry from Stirling North station, it stands at 7.7m.

"It came out of use in 2008 and we rebuilt and repainted it," he says. "It was part of the Stirling-Alloa line and was in operation from when it was built in the late 19th century until it was taken down a week before it came in here. If you go on the northern railway lines through Scotland, you'll still see signals like this in action."

"The issue when it comes to objects like this is that they won't survive if someone doesn't acquire them," adds Jackson. "It would be the end of the line because there is no resale value and not enough metal for scrapping. It's about preserving and celebrating history that otherwise might die."

Beside the signal gantry is a magnificent 1950 Formula 3 racing car that will also be mounted on the Wall. "It's made by a company called Potts in Bellshill, Lanarkshire," says Cockburn, who spent many hours removing the heavy corrosion on the brakes. The car was commissioned by a wealthy Paisley garage owner to discourage his son from taking up motorcycle racing. The team reckon only five of these have survived the production run of 34. "The Potts were undertakers who had a garage as well. Joseph Potts even put his own casting on the nose of the car. It was a successful motor in Scotland – until it went to England, where it wasn't fast enough." He laughs.

Next door, we meet a conservator who is working on an Iranian shield, part of a lavish suit of armour inlaid with gold with Koranic quotations. It's one of six special focus objects on the Wall (the jawbones are another) that will be explained through labelling. "This single suit of armour was actually made by four different craftsmen over a period of 150 years," says Jackson, before dragging me away to the next room where the heaviest object on the Wall is located: a working model of the Wylam Dilly locomotive made in the Museum workshops in 1885 and weighing a considerable 580kg.

"We have the real Wylam Dilly in the Connect Gallery," says Stuart Mcdonald, head of engineering conservation. "It's one of the two oldest surviving locomotives in the world. Eight working models will be included in the Wall. There will be touch panels so people can see them in action. We're so pleased to see these models going out on display again. Kids love them."

Over in artefact conservation we meet Ticca Ogilvie who, alongside her small, steady-handed team, has put in many hours of work cleaning and restoring a set of delicate Blaschka glass objects of sea slugs (the smallest item on the Wall), jellyfish and other marine life. She has also been cleaning a series of rare Charles Rennie Mackintosh lamps. "It was quite a challenge to remove the brown sticky nicotine from the outside of this one," she says. "And this one has obviously fallen at some point and was completely buckled. It arrived here in a damp cardboard box."

"If I had to choose a favourite object from the Wall, it would be the Mackintosh lamps," admits Jackson with all the guilt of a parent picking a favourite child. "This lamp is from Francis Newbery's mother-in-law's house in the West End of Glasgow. He was the inspirational head of the School of Art and he gave Mackintosh a small commission to do some things for his mother-in-law. We got in there in 1987 and amongst the 1930s wallpaper and velour curtains, we saw this. These lamps have never been shown before." The larger objects will be fixed but the smaller ones, such as the dozens of jars of marine invertebrates and molluscs in spirit, will rotate. Others will be reflected on light boxes.

The Wall of Wonders will only showcase a drop in the ocean of the National Museum's huge collection – less than a tenth of a percentage, Jackson guesses. Yet it represents something much bigger in its scope and vision. "This is about bringing out objects that otherwise wouldn't find a home," says Jackson as we head off to the spirit lab to examine the curled octopuses and giant clams.

"It invites people to ask the question of why is all this stuff in Scotland? What is it? How did it get here? And in asking those questions you realise the Wall represents centuries of Scottish and global achievement."