Besides photographic film as the standard recording material, photographic paper can also be used (the length of exposure must be increased). Polyester-coated paper has proven to be especially successful, because it is so easy to process; thus photographs up to a size of 300 x 130 cm. have been made in one piece. Thin sheets of aluminium, brass or tin can be used as filters against scattered radiation or to reduce the field of contrast. Stereoscopic radiographs are better for deflning the structure of complicated three dimen sional objects. Various methods of taking and viewing the two stereoscopic photographs are discussed. Experience has shown that the difference between the dimensions of the original and those of the X-ray photograph seldom exceeds 3%! -- AATA