Where the agent has received no appointment from the principal, but the principal has led another to believe, that he has invested the so-called agent with authority, the principal will be estopped from denying the existence of the agency, where another person has dealt with the agent, believing he is fully qualified to act for the principal.5 The third person is bound however, to exercise ordinary prudence and care, and must not rely too much on surface appearances. Much depends on the nature and the circumstances of each particular case, and each particular case would be governed to a large extent by the circumstances of that case.