Doc and assistant checking amount of nourishment and pulse of "head-less" woman.  Can you detect how this illusion is created?   Circa 1930's

Crowds gather at a London store in the window of which is an apparently headless woman.  The effect is heightened by a tube
leading to the throat.  Through this tube goes the food which the woman is supposed to consume and the amount of nourishment
is indicated on dials.  The camera fails to reveal the trick, but it appears to be similar to the head-without-a-body illusion featured in circus sideshow for many years, which is accomplished with the aid of mirrors.