Benjamin & Bifocals

The bifocal  was  invented  by  Benjamin Franklin  in the  eighteenth century.

Benjamin_Franklin_1767

At that time,  when someone wearing  glasses  became presbyopic,  a separate pair  of  reading  glasses  was  prescribed. When Ben  Franklin  found  himself  in  that situation,  he  felt it was  inefficient  to  have  to  change glasses  when alternating  his  vision from  distance  to near  and vice  versa.  Franklin  realized  that when viewing  at  distance  through his  distance  glasses  he  was  using  the  top  portion of  the  lenses, and when reading  at  near  with the  reading  glasses  he  was  using  the  bottom  portion of the lenses.
Therefore, he decided  to  cut  each  distance and  reading  lens  in half  and  glue  them  to each other, with the distance  lens  at  the  top and the  reading  lens  at  the  bottom. Thus, he  had  two pairs  of  glasses  in one  — and the  bifocal  was  invented!

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