The extent to which a witness can be required, on cross-examination, to testify to matters not directly in issue, *588must necessarily be left, for the most part, to the judicial discretion of the court in which the trial is had. It is undoubtedly true that, if a witness produces any writing to assist his memory, he may be compelled to submit it to the inspection of the opposite pprty, to enable him to see whether it is a proper memorandum for the purpose, and to cross-examine upon it. Especially is this so when he professes to be able to testify only by aid of the writing. But this rule does not involve the duty of exposing everything contained in a book in which his memorandum is kept. He is only bound to show such parts of it as he consults to aid his memory, or such as relate to the subject of his testimony. Private entries on other matters, though contained in the same book, are not thereby made parts of the writing which he produces. Hardy’s case, 2 C. & P. 604, note.

In this case, the witness did not produce the book to assist him in testifying, although he said that he had consulted it to enable him to testify, and was only able to state the transaction by its aid. He produced it by the request of the defendant or. cross-examination. It was then going as far as any authority will warrant, to allow the defendant and the jury to inspect the entries relating to the matter in issue; and the other contents of the book, which the witness said were private, and not concerning the case, he had a right to keep back. It was for the presiding judge to determine what parts of the book were material ; and if he was satisfied with the statement of the witness and refused to permit the cross-examination to extend farther the refusal is not the subject of exception.

Exceptions overruled.