Examination of witness respecting previous statements in writing
19A witness may be examined as to previous statements made by him in writing, or reduced into writing, relative to the subject matter of the cause, without such writing being shown to him; but if it is intended to contradict such witness by the writing, before such contradictory proof can be given, his attention must be called to those parts of the writing that are to be used for the purpose of so contradicting him; and it is competent for the judge at any time during the trial to require the production of the writing for his own inspection, and he may thereupon make such use of it for the purposes of the trial as he thinks fit.