On 17 June he set off again by himself .
Next day reached 20,000 feet ( 6,100 m ) where he met one of his party 's groups who were amazed to find him so well .
On 17 June he set off again by himself and next day reached 20,000 feet ( 6,100 m ) where he met one of his party 's groups who were amazed to find him so well .