The Flammarion

 An engraving.

 Quoted from Wikipedia:
 (in) English: 
 "The Flammarion engraving is a wood engraving by an unknown artist that first appeared in Camille Flammarion's L'atmosphère: météorologie populaire (1888). The image depicts a man crawling under the edge of the sky, depicted as if it were a solid hemisphere, to look at the mysterious Empyrean beyond."

 The caption underneath the engraving translates to:
 "A medieval missionary tells that he has found the point where heaven and Earth meet…"
 Date    1888
 Source    Camille Flammarion, L'Atmosphère: Météorologie Populaire (Paris, 1888), pp. 163
 Author    Anonymous".
 This image is in the public domain.

 "The print depicts a man, clothed in a long robe and carrying a staff, who is at the edge of the Earth, where it meets the sky. He kneels down and passes his head, shoulders, and right arm through the star-studded sky, discovering a marvellous realm of circling clouds, fires and suns beyond the heavens."

 "The caption that accompanies the engraving in Flammarion's book reads:

A missionary of the Middle Ages tells that he had found the point where the sky and the Earth touch...[1] "