Gosse left Alice Springs on 21 April 1873 with a party comprising Edwin S. Berry (another AEI boy) as second-in-charge; Henry Winnall and Patrick Nilan, three Afghans (Kamran, Jemma Kahn, and Allanah), an Aboriginal boy named Moses from The Peake.
They found a spur along which it was possible for Gosse and Kamran to scramble two miles to the summit, 1,100 ft (340 m) above the surrounding country.
[4] The party reached a point 600 miles (970 km) west of the Transcontinental Telegraph Line and were forced to return due to lack of available water.
[18] A sister-in-law, and also niece, Helen (1877–1909), and her mother (William's sister), were lost at sea on the ill-fated SS Waratah.
[19] Other descendants include former Australian Minister for Foreign Affairs and Liberal Party leader Alexander Downer.