Description: Patent for improvements in refracting-telescopes in which the instrument may be readily and accurately focused by adjustment of the lenses within the telescoping sections; and by having one or more perforated diaphragms for avoiding errors due to spherical aberration, an adjustable and removable transmitter for the light passing through the object-glass, for the purpose of toning the quantity of light. Illustration is included.
Date: April 28, 1891
Creator: Riddle, William Nelson
Item Type: Refine your search to only Patent
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