Bentley photographed more than 5,000 jewel-like snow crystals
Ten of the pioneering photos of snowflake crystals US farmer Wilson A Bentley began taking more than a century ago are to be sold in New York.
Bentley (1865-1931) is credited with capturing the first images of single snowflakes on camera. He made thousands of the jewel-like prints, no two alike.
His photomicrography technique involved a microscope and a bellows camera.
He caught pneumonia in a blizzard and died just weeks after the publication of his book Snow Crystals.
The sale of his crystal images is a rare event, the Associated Press news agency reports.
Chicago art gallery owner Carl Hammer is selling them along with 16 of Bentley's winter scenes at an antiques show at New York's American Folk Art Museum.
"They're remarkably beautiful," said Mr Hammer.
"There are imperfections on the outer edges of the image itself and on the paper, but the images themselves are quite spectacular."
'Good for 100 years'
Snowflake expert Kenneth G Libbrecht said the photos did not meet modern standards because of the "crude equipment" Bentley used.
"But he did it so well that hardly anybody bothered to photograph snowflakes for almost 100 years," Mr Libbrecht added.
Bentley, who was known as The Snowflake Man, wrote in 1925: "Under the microscope, I found that snowflakes were miracles of beauty and it seemed a shame that this beauty should not be seen and appreciated by others.
"Every crystal was a masterpiece of design, and no one design was ever repeated. When a snowflake melted, that design was forever lost."
Mr Libbrecht said the method of singling out a crystal to photograph had not changed.
"You basically let the crystal fall on something, black or dark-coloured, and then you have to pick it up with a toothpick or brush and put it on a glass slide," he said.