Electric Retinoscope Catalog - DeZeng 1912

This is a four page flyer describing four models of DeZeng retinoscopes. The retinoscope was used to determine the refractive state of the eye. The adaptation to electricity in the early 1900s made ophthalmic instruments vastly more useful. Previously oil lamps and candles had been used to provide illumination from reflecting mirrors.
The DeZeng company eventually became American Optical and most recently Reichert company.
This is a downloadable pdf file (Free Acrobat Reader is needed to view it).