Why do old cameras have to be wrapped in cloth to take pictures? Press the button with your hand like a balloon. Is it an air switch? How does this switch work?

That's a frosted glass camera on the back of the camera. This is not new. Even today, many professional studios still use this camera. Because the light is directly focused on a large piece of frosted glass on the back of the camera, it is dim. Generally, a cover is needed to cover the photographer's head and the back of the camera together to see more clearly.

The pneumatic shutter is also purely mechanical, and the airbag is used to trigger the shutter.