Xylotomy is the preparation of small slivers of wood for examination under a microscope, often using a microtome.
It is useful for providing forensic evidence in some criminal cases where finding a fragment of wood on an individual and matching it to a weapon used in a crime would be helpful.
[1][2] During the trial of Bruno Richard Hauptmann, accused in the Lindbergh kidnapping during the 1930s, the xylotomist Arthur Koehler was able to provide crucial evidence by linking a piece of pine from a ladder used in a kidnapping to one particular factory whose machinery was defective, and from there to one particular lumberyard.
[3] Koehler searched for eighteen months for the yard, and presented his evidence dramatically in court by presenting the court with a chalk rubbing of the samples, which he made there and then, demonstrating that they were identical.
Identifying the species of a piece of wood is not always easy, in which case a xylotheque may provide samples with which the xylotomist can compare his own.