Although optical reflexion and refraction of X-rays have been known for more than twenty years, they have so far found only one significant, although very important, application, namely, the spectroscopy of X-rays by means of optical gratings. But there is at least one other problem which should be solved by optical methods: the production of a finely focused beam which could be used to investigate both the action of X-rays on biological and other objects and the small-angle scattering from large molecules or fine powders.