Question

How do we know that the pinhole camera existed before the nineteenth century?

Answer 1

Some say it existed as early as 5th century BC.
Read about it here:

http://www.pinhole.cz/en/pinholecameras/whatis.html

Answer 2

thanx

Answer 3

You're welcome! :)

Answer 4

Image result for when did the pinhole camera invented
Between 1000 and 1600, men such as Ibn al-Haytham, Gemma Frisius, and Giambattista della Porta wrote on the pinhole camera, explaining why the images are upside down. Around 1600, Giambattista della Porta added a lens to the pinhole camera.