• Manwiller, F.G.
  Southern Forest Experiment Station, Alexandria, LA
  

A technique originated by Preston, is explained for determining fibril angle of the secondary wall layers of fibers. A polarizing microscope equipped with Senarmont compensator is used to measure birefringence of the wall layers in a series of sections cut at various angles to the long axis of the cells. Enough measurements are taken on each section to give a representative average. A plot of birefringence against section angle for each layer defines a curve. Fibril angle in the layer is estimated equal to the section angle corresponding to the maximum of this curve.