M�canisme de la physionomie humaine

I have recently learned of the Italian born French doctor Guillaume-Benjamin Duchenne. Renowned for his discovery of hereditary muscular dystrophy. By using high voltage electrical currents on live humans from an inductor coil, he was able to study facial expressions. He deduced that genuine display of happiness lie in the contraction of the muscles of the mouth and of the cheeks and eyes. They form crow’s feet, hence the term “Duchenne smile”.

Here photography meets science in the name of research. To demonstrate the effects and prove his theory Duchenne of course used the only 'truthful' medium to do so, the camera. Duchenne published the photographic examples in his book entitled "M�canisme de la physionomie humaine" (1862)
The results simultaneously intriguing and funny!