Question

18th century camera obscura; B is the lens and M is the mirror.
What is use of mirror in camera of 18 century.​

Answer 1

Answer:

A camera obscura (plural camerae obscurae or camera obscuras, from Latin camera obscūra, "dark chamber")[1] is a darkened room with a small hole or lens at one side through which an image is projected onto a wall[2][3] or table[4] opposite the hole.[2][3]

Illustration of the camera obscura principle from James Ayscough's A short account of the eye and nature of vision (1755 fourth edition)

An image of the New Royal Palace at Prague Castle projected onto an attic wall by a hole in the tile roofing