“…8, Column 5, is shown the effect, on a series of calculated images, of summing images from scattering calculations for 11 angles of incidence across the cone of convergence. The summation consisted of addition of intensities, and not phases and amplitudes, since the source can be regarded as incoherent and, in this respect, is exactly similar to diffraction in a convergent-beam diffraction camera (Cockayne, Goodman, Mills & Moodie, 1967). As can be seen, the effect of divergence is zero at zero defect &focus and is increased as the absolute value of defect of focus increases.…”