During the late 18th century, France decided that their present forms of execution--such as hanging, beheading by axe, and the "breaking wheel"--were cruelly designed to inflict pain as well as death. Determining that the death sentence should be quick and painless, French leaders looked toward other forms of execution: Among those under consideration were the
Italian Mannaia (or Mannaja), the Scottish Maiden and the Halifax Gibbet, which was fitted with an axe head weighing 7 pounds 12 ounces (3.5 kg). (Wikipedia, Guillotine)
After some debate about whether the killing blade of this proposed new "beheading machine" would be triangular, crescent or straight-edged, a straight-edge blade dropped at a 45 degree angle was selected. German harpsichord maker Tobias Schmidt built the prototype. Its designers included the King's physician, Antoine Louis; a French court officer, Laquiante; and the man for whom the device would eventually be named--physician Joseph-Ignace Guillotin. Humane for its time, the guillotine was first successfully used in April 1792, and it continued as France's official form of execution until 1981. Other nations, particularly Germany, also continued its use until the 1960s.