Stereoscopic x-ray work demands the taking of two radiographs from different angles and the subsequent susperimposing of the plates by viewing them through prisms or in a Wheatstone stereoscope. After exposure the first plate must be removed and a second one must be substituted.
With the improvement of x-ray apparatus it has become possible to make two radiographs of the chest in the space of a few seconds; that is, while the patient suspends respiration, and thus to obtain true stereoscopic pictures of the chest. But the problem of quickly removing one photographic plate and substituting a second has been a serious hindrance in this work.
The following simple method has been devised to change the plates: A sheet of lead, 1/8 inch thick, is provided on both sides with small clamps sufficient to hold a photographic plate against each aspect. This sheet of lead is then suspended at