(CNN) Some of the most prized possessions of late British physicist Stephen Hawking, including a copy of his Ph.D thesis and an early wheelchair, have sold for much more than expected at an auction by Christie's in London.
In total, 22 items that belonged to Hawking raised $1.8 million (£1.38M) on November 8 as part of the online sale "On the Shoulders of Giants," which also featured papers from Isaac Newton, Charles Darwin and Albert Einstein.
Hawking's 1965 Cambridge University Ph.D. thesis, "Properties of Expanding Universes," was one of the most sought-after artifacts at the auction and raised $763,300 (£584,750). The thesis was one of five existing copies and was expected to fetch up to $195,800 (£150,000), according to Christie's.
Handwritten on the front is a note from Hawking confirming that it is his original work.
Another big hit at the auction was an early motorized wheelchair used by Hawking after he was diagnosed with the neurodegenerative disease amyotrophic lateral sclerosis (ALS) in 1963.
The wheelchair raised $387,480 (£296,750), almost 20 times more than pre-auction estimates of up to $19,500 (£15,000). Proceeds will be donated to the Stephen Hawking Foundation and the Motor Neurone Disease Association, Christie's said.
Hawking, who was also a cosmologist, astronomer, mathematician and a prolific author, died in March at age 76. After he was diagnosed with ALS, also known as Lou Gehrig's disease, when he was 21, doctors only gave him a few years to live.
"Hawking initially resisted the idea of using a wheelchair in the late 1960s; by the late 1970s, he was using motorized models like the present example, and was even renowned for being a rather wild driver," said Christie's.
"By the late 1980s he was at the height of his fame, and given his extensive travels to conferences and public events, as well as the scope of his intellectual explorations of space-time, this is arguably both literally and metaphorically the most-traveled wheelchair in history. "
One of his most famous works was his landmark book a "A Brief History of Time," which sold more than 10 million copies. At the auction, a copy "signed" with Hawking's thumbprint raised $89,750 (£68,750), way above the $3,900 (£3,000) estimate.
Other personal belongings included a bomber jacket, which fetched $52,200 (£40,000) and a collection of his medals, which went for $387,360 (£296,750).
Perhaps more surprising, among some of Hawking's possessions was a script from an episode of "The Simpsons," which raised $8,160 (£6,250).
"Stephen Hawking made four appearances in The Simpsons over a period of 10 years, something he joked made him more famous than anything he had done in science," said Christie's on its website. "A small plastic model of his yellow Simpsons incarnation had pride of place in his house." This particular episode was aired on September 26, 2010.
"We are very pleased to have the assistance of Christie's to help us with the important matter of managing our beloved father's archives and his unique and precious collection of personal and professional belongings, chronicling his life and work," said his daughter Lucy Hawking in a statement before the lot took place.
She said the auction would give "admirers of his work the chance to acquire a memento of our father's extraordinary life in the shape of a small selection of evocative and fascinating items."