Atlas favoured by Columbus goes on sale for £1 million

Scotland is shown floating off Northumbria and Asia is twice its actual size but, for an atlas based on 1,300-year-old data, it is a remarkable testimony to the golden age of exploration.

It is one of only two privately owned copies of the 529-year-old Cosmographia, the world's first printed atlas, and is likely to set an auction record next week when it is sold at Sotheby's in London. It was saved from destruction in 2004 when the home in Oxfordshire of its late owner, Lord Wardington, was damaged by fire.

The leather-bound volume has been estimated to sell for up to £1m but could exceed £1.5m. It was printed in Renaissance Italy according to the calculations of Claudius Ptolemy, known as the Father of Geography, who worked in Alexandria, Egypt, around AD150.

Based on the navigational records of seafarers and travellers in the ancient world, the hand-coloured atlas unsurprisingly has its inaccuracies. England is shown as a long spindly land mass jutting into the Bay of Biscay while a lop-sided Scotland juts out of Northumbria. It vastly overestimates the size of Asia, omits the as-yet-undiscovered New World and underestimates the size of the planet.

But the Cosmographia is nonetheless considered one of the most important works in cartography. It became a standard text for Renaissance-era explorers for more than a century after it was first printed in Bologna in 1477. Its significance in the annals of exploration is underlined by the legend that its second edition was used by Christopher Columbus on his voyage to the Americas.

Dr David Goldthorpe, a map specialist at Sotheby's, said: "The surprising thing about the atlas is how accurate it actually is given the technology that was available to Ptolemy. All he had to base his calculations on was the data from sailors and travellers, but the result is nonetheless a recognisable atlas of the world as it was known at the time.

"The legend has it that Columbus used the second edition in his voyage. Because the atlas showed the world as smaller than it actually is, Columbus was convinced he had reached India rather than America."

The 61-page atlas includes 26 maps drawn up by medieval cartographers based on the descriptions of Ptolemy, who posited that the world was spherical rather than flat.

The atlas's emergence on to the open market is likely to provoke a scramble in the world of rare map collecting. Scarce supply has even helped generate a spate of thefts from public libraries in recent years. The world record for an atlas stands at £1.5m for a 16th century "Doria" atlas, named after a Genoese family of that name. The price was achieved at the first sale of Wardington lots at Sotheby's last year.

The sale of the 1477 Cosmographia represents the dissolution of one of the greatest map collections in Britain following the death last year of Lord Wardington. The peer and scion of a Quaker banking family built on a collection inherited from his father. His library of 700 volumes, with some 60,000 maps, was only saved from the fire at his 17th century manor house by the intervention of neighbours, who formed a chain to pass the books to safety after an electrical fault set the roof ablaze.