Fascinating information; thank you, Dave! (In an incredible coincidence, in connection with System 3, you mentioned a process called “imbibition”. It’s Friday night and I, too, am imbibing.)
I understand that the main reason driving innovation was fire. The lamps in the projectors had to be very powerful. And the earlier cinemas went up regularly. And it's the reason for the multiple projectors for they would eventually heat to the point of explosion.