Gedani

$Gedani: Hevelius observing through refracting telescope$

Hevelius observing through refracting telescope

Hevelius's 150-ft (16.240m) telescope being erected

$Prints of Hevelius's plan for a tower observatory, showing various telescopes, including his 150-ft (16.240m) refracting telescope. From Selenographia by Johannes Hevelius (Gedani, Gdansk, Danzig, 1647)$

Hevelius's plan for a tower observatory, showing

$Gedani: Hevelius observing with a wooden-tubed refracting$

Hevelius observing with a wooden-tubed refracting

$Prints of Method of projecting the sun's image through a refracting telescope onto a screen in a darkened room (camera obscura) in order to study sunpots$

Method of projecting the sun's image through a

$Gedani: Projecting the sun's image through a refracting$

Projecting the sun's image through a refracting

Observations of sunspots, May 1644. On right is

Johannes Hevelius's dissertation, de Nativa Saturni