Abstract
Horizontal micro-projection of the cross-sectional image on. to a vertical ground glass screen presents a method whereby a representative field can be measured systematically. The shadow of a coördinate scale is superimposed without magnification upon the same ground glass screen. The observer sits behind the screen; therefore shadows cast by his body do not blot out part of the projected image.
By means of a transparent scale, which has special rulings on it that are at right angles to cach other, both the minor and major diameters of a fibre in cross-section can be measured directly in microns with one setting of the scale. Only five minutes are required to measure 100 fibres.
The use of a bundle sizer is described for obtaining the same number of fibres. This instrument is intended for use with metal cross-sectioning plates and facilitates making of the same size sections.
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