UNIVERSAL HISTORY ARCHIVE / UIG / SCIENCE PHOTO LIBRARY UNIVERSAL HISTORY ARCHIVE / UIG / SCIENCE PHOTO LIBRARY
How to construct a mounting for a refracting telescope so that the Sun's image could be projected onto a screen and sunspots safely studied. A second screen at R blocked out indirect sunlight and made it possible to use the instrument without a camera obscura. From Rosa Ursina by Christoph Scheiner (Bracciano, 1630). Engraving.
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