For speculum, or "keyhole," work the head mirror and a separate source of light comprise the basic means of illumination.
However, from the standpoint of convenience the head mirror has certain disadvantages—the principal one is that the relationship between the source of light, the observer's head, the position of the mirror and the object to be illuminated must be kept constant. A change in position of one of these necessitates an adjustment of one or more of the other factors.
The light here presented represents an attempt to approximate the good qualities of the head mirror and at the same time eliminate some of the disadvantages.
The concave head mirror in operation becomes a multiple point source of light, which is directed at an object. The illuminated object is viewed through the beam of light.
The light here described has been constructed on this basic principle. It consists of multiple
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