patent vs. latent ambiguity

Sir Francis Bacon, in his elements of common law, is the author usually referred to on this distribution of ambiguities, into patent and latent; the former appearing on the face of the instrument, and not to be removed by extrinsic evidence, but only, in the language of the author, 'to be holpen by construction or election;' the latter raised by reference to extrinsic circumstances, and remediable by the same means. It would perhaps be a more convenient, and certainly a more intelligible distribution of the doctrine on this subject, if the cases were divided into positive, relative, and mixed.