One of the negative things about technological progress is when something that was originally intricate and mechanical becomes a ubiquitous piece of cheap technology. This happened in the 70s with watches and more recently has happened with cameras.A modern day spy camera is not that interesting, but the miniature ones here are, similarly the wide range of hardware solutions create much more design diversity in early cameras, from the giant 900lb box camera to the bizarre miniature ones developed for carrier pigeons, from gun like trigger activated shutters to a propeller powered film advance mechanism for a camera mounted below an early aircraft.