Mixed-image longitudimetry: a new method of length measurement in microscopy.

A simple and inexpensive instrument called a longitudimeter for measuring distances in microscopy was constructed from a precision map-measuring device and an electric lamp positioned eccentrically on a stand. A precision better than 1% was readily obtained in measurements of the perimeters of trabecular surfaces in cancellous bone. Mixed-image longitudimetry was devised for length measurements in cancellous bone, but the method seems suitable for a wider application in quantitative microscopy.