Enigma Number 171 On the beach

摘要

Clearing my attic, I found my old 8mm cine-projector and films of our children. It still worked; The film moves through the projecting gate at an essentially constant speed from the stock spool to an identical take-up spool. The empty spool has a 4-centimetre diameter and the spool when full has a diameter (to the outside of the film) of 12 cm. The playing time is 17 minutes. Each spool has five spokes, so it is easy to compare speeds of rotation.