Edward Mohun (sometimes referred to as Mahun) was an explorer and surveyer for the CPR surveys. He had a civil engineering degree.
It appears that he went on to work for the British Columbia Department of Lands and Works. (See a BC map published in his name in 1884 ). There is an 1879 reference saying he was Surveyor in Charge of Indian Reserve Surveys at that time) and published a number of maps of Indian Reservations.