The theory and application of diffraction by long, x-ray wavelengths are discussed. Four methods obtaining the diffraction pattern are described, namely (1) the double-crystal spectrometer, (2) the annular slit system, (3) the concave mica, point-focusing monochromator, and (4) the total-reflection, point-focusing system. The design and construction of the total-reflection equipment is described in detail. This method is applied to the measurement of the Dow latex particles
