The fact the defendant offered to show was collateral to the issue, and its exclusion raises no question of law. *592 All children begotten while their parents are living together as man and wife are presumed to be legitimate, and this presumption cannot be rebutted by showing that the wife was guilty of adultery during the period of gestation. Parker v. Way, 15 N. H. 45; Hemmenway v. Towner, 1 Allen 209; Cross v. Cross, 3 Paige 139,—23 Am. Dec. 778; Rex v. Luffe, 8 East 193.

Exception overruled.