Also known as a palm pistol as this revolver is easily concealed in the palm of one's hand. The stubby barrel protrudes between the firer's index and middle fingers, and the gun is fired with a squeezing action. The circular magazine came in various sizes with 4-shot and 7-shot versions known and rotated to automatically load the next round when fired.
While not terribly accurate as it had no sighting facility and hence could only be aimed as one points an arm, it was effective in assassinating William McKinley in 1901.
This is not to be confused with the Smith & Wesson .32 caliber "Lemon Squeezer" Safety Hammerless which is very much like a typical revolver of its time.
This style of pistol is similar in application to a derringer