Use of a Prismatic Binocular for Viewing Near Objects

A FEW years ago, with a view to the observation of close objects out of doors, I procured some glass adapter lenses for use on the object glass of the half of a prism binocular (× 12) which I carried about with me. Finding, however, that this method involved the use of several glass adapters, and that with it I had to know the exact distance of my objective… (More)