For the most precise astrometric work it has proved necessary to use only the great refracting telescope, although such an instrument still falls short of perfection. The color curve is so severe that faint companions may become unobservable, or a dependence on spectral type may be introduced. Spectroscopic and spectrographic work are also affected. The author proposes here a revival of interest in the Schupmann medial telescope, redesigned for the requirements of modern researches, and

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... s the pros and cons of such an instrument for astrometric applications.