State v. Everson
In State v. Everson, 166 Wash. 534, 7 P.2d 603 (1932), the walking stick of the deceased was introduced into evidence in a manslaughter case, and some or all of the jurors used a magnifying glass to examine it more carefully. 166 Wash. at 535.
The Court refused to reverse the verdict, concluding that "the jury merely more critically examined the walking stick by the aid of a magnifying glass. This did not put them in possession of material facts which were not already in evidence."
Rather, the Court compared their use of the glass to jurors' use of their reading glasses to examine the end of the stick, which nobody would question would be proper.
"In using a magnifying glass rather than a reading glass, the only difference would be the greater magnifying power of the former." Id. at 537.