Estoppel prevents an acceptor, bailee or licensee from denying the apparent authority relied upon by third parties. Estoppel prevents an acceptor of a bill of exchange from denying the drawer s authority to draw or endorse, and prevents a bailee or licensee from denying that the bailor or licensor had authority to make the bailment or grant the licence at its commencement; however, the acceptor may deny the bill s authorship, and a bailee who delivers goods to a third person may prove that person s right against the bailor.