Charles-Henri Sanson was the chief executor of Paris for more than 40 years, beginning in the mid-1750s and retiring in 1795. During this time he personally despatched almost 3,000 people. Like most executioners, Sanson inherited the job from his father and passed it on to his own son.

Sanson’s grandson, Henry-Clément (1799-1889) later published a memoir focusing on his family’s notorious contribution to 18th century France. In this extract, Sanson describes the development and adoption of the guillotine in 1791-92 – with some ironic help from Louis XVI:

“”Doctor Guillotin’s special object was the adoption of an innovation. Disgusted as he was at the sight of the gibbet, which exhibited a corpse for hours before the mob, he was determined to substitute a punishment by which suffering would be mitigated. He saw no better means for the furtherance of his object than decapitation. It had hitherto been reserved for a privileged class and, in all respects, was a more manly and natural way of inflicting death. But then the executioner’s sword had often failed to accomplish its work; the hand was apt to tremble and only machinery could give a guarantee of unswerving precision.

Guilliton’s purpose then was to discover the best decapitating machine [and] he pursued it with untiring zeal. [Gullotin’s proposal] was sent to the Committee of Seven and became law in 1791, when decapitation was definitely adopted; but the process by which decapitation was to take place was not indicated… Charles-Henry Sanson insisted on the urgent necessity of a machine which would keep the sufferer’s body in a horizontal position and ensure prompter and safer operation than could be expected of hand work. This was precisely what Dr Guillotin was seeking and he visited my grandfather to ask his advice… They examined everything which, in the past and in other countries, could realise the idea of the machine…

[Guillotin] described the new apparatus in the [National Assembly] sitting of April 30th 1791. Carried away by enthusiasm, he made use of expressions which excited loud laughter and almost imperilled the success of his cause. He said that the culprit would only feel “a slight freshness on the neck”. He added: “With this machine, I chop your head off in a twinkling and you do not suffer”…

The King and his physician expressed a desire to examine the plan of the machine proposed by Dr Guillotin. [On inspecting the plans] the King said: “The knife has the shape of a crescent. Do you think a knife thus shaped would be suitable for all necks? There are some which it certainly could not cut”… Charles-Henri was struck by this remark and looking at the King’s neck, he saw that its proportions were just those which justified the King’s remark… “The gentleman is quite right”, answered my grandfather. “The knife is not what it should be.” The King smiled with an air of satisfaction and taking a pen which lay on the table, he rectified the plan and substituted an oblique line for the crescent…

On March 20th the [Legislative] Assembly passed the report and [ordered] the construction of the first decapitating machine. The work was done by a carpenter named Guidon, who charged 5,500 francs. When the guillotine was finished, my grandfather and two of his brothers went to the prison of Bicêtre to make experiments on three corpses… The three corpses were decapitated, one after the other. The first two experiments with the oblique knife succeeded; the third, with the knife shaped as a crescent, failed. A week afterwards, my grandfather had occasion to test the new system on a man named Pelletin, sentenced to death for theft and attempted murder.”