The guillotine was introduced to France in 1792, and consisted of a large heavy knife blade that could be raised and allowed to fall between two grooved posts connected at the top by a crossbar. 
Guided by the grooves and speeded by its weight, the blade came down with such a force and precision that it neatly severed the head of anyone beneath it. Death by guillotine was instantaneous, making it almost painless.
Dr. Louis, the inventor of the guillotine, showed Louis XVI the first model which had a straight horizontal blade. Because things of a mechanical nature tickled the King’s fancy, Louis instructed him to make the blade diagonal, in order for a better cut; thus contributing to the advancement of the device that murdered him.
Excerpt from Victor Hugo's Les Misérables in regards to the guillotine: "The guillotine is the law made concrete; it is called the Avenger. It is not neutral and does not permit you to remain neutral. Whoever sees it quakes, mysteriously shaken to the core. All social problems set up their question mark around that blade. The scaffold is vision. The scaffold is not a mere frame, the scaffold is not an inert mechanism made of wood, iron, and ropes. It seems like a creature with some dark origin we cannot fathom, it is as though the framework sees and hears, the mechanism understands, as though the wood and iron and ropes have their own will. In the hideous nightmare it projects across the soul, the aweful apparition of the scaffold fuses with its terrible work. The scaffold becomes the accomplice of the executioner; it devours, eats flesh, and drinks blood. The scaffold is a sort of monster created by judge and carpenter, a specter that seems to live with an unspeakable vitality, drawn from all the death it has wrought."
"The National Razor"
"The Hungry Lady"
"The She-wolf"
"Madame Guillotine"
"The Widow"
