Of the many different kinds of viewers available in museums very few allow composite x-radiographs, made of several large negatives, to be viewed together. The illuminator described has a viewing area of 90-120 cm., and a method for cutting and mounting radiographs is given. The illuminator can also be used for stereo-x-rays in conjunction with a hand-held stero-viewer, and for the examination of engravings and drawings by transmitted light. -- AATA