- GeoRef, Copyright 2004, American Geological Institute. Reference includes data from Bibliography and Index of North American Geology, U. S. Geological Survey, Reston, VA, United States
Directions are given for constructing a set of scales which may be overlaid on photomicrographs to enable direct readings of vector quantities. As a separate scale is required for each objective, the author recommends making a set of scales for all the objectives of a given microscope-camera combination to be kept with the microscope. Relatively inexpensive to construct, these scales make photomicrographs far more desirable for studying acid-insoluble microfossils.