Long before Tenzing Norgay Sherpa and Edmund Hillary started their mountaineering careers, Edward Felix Norton and Theodore Howard Somervell set a world altitude record in the spring of 1924.

The two British climbers reached about 300 metres below the Everest summit without supplemental oxygen. But since they were so breathless and exhausted they couldn't carry on any further. For more than five decades after that spring no one crossed the last 300 metres without supplemental oxygen.

Norton and Somervell were expert mountaineers of their generation. They ascended Mount Everest wearing hobnail boots and tweed jackets, without the comfort of insulated boots or down jackets that today's climbers have access to. In the 1924 expedition, there was no oxygen equipment that worked and climbers were still experimenting with various machines.

What they accomplished that day in terms of exposing the human body to such high altitude and cold was a medical and physiological landmark. The difficulty breathing at these altitudes is captured in many documentaries where the excessive panting of the climber is the dominant noise in the background. This panting is bad enough even with oxygen cylinders.

Although Sherpa and Hillary finally climbed Everest in 1953, they had oxygen bottles to support them. It was only in 1978 that Italian Reinhold Messner and Austrian Peter Habeler completed the final 300 metres that had eluded Norton and Somervell without supplemental oxygen. But why did it take 54 years for climbers to successfully ascend to the top without additional oxygen?

Scientists in the 1920s and 30s believed that without supplemental oxygen, the human body would have reached its point of exhaustion and even taking a single step would be impossible. So conquering Everest was out of the question This conclusion arose from the maximum oxygen uptake which determines a person's level of fitness.

However, the calculations were misleading as Messner and Habeler proved. Other medical reasons were the overpowering hypothermia (cold temperatures) and hypoxia (lack of adequate oxygen) that caused climbers to turn back.

Clearly climbers like Norton and Somervell were outstanding human beings. Norton went on to become the governor of Hong Kong, and Somervell gave up a promising career as a surgeon in England to become a medical missionary in South India.