In many fantasies spanking machines have it’s own, very useful, purpose. Throughout the history many illustrations have been made about this subject. In the early days corporal punishments were common events such as public whippings.
The philosopher Jeremy Bentham ( (1748-1832) ) wrote in his book The Rationale of Punishment about the benefits of a machine that would make the work of more easy.
Of all these different modes of punishment, whipping is the most frequently in use ; but in whipping not even the qualities of the instrument* are ascertained by written law : while the quantity offeree to be employed in its application is altoge
ther intrusted to the caprice of the executioner.
He may make the punishment as trifling or as severe as he pleases. He may derive from this power a source of revenue, so that the offender will be punished, not in proportion to his offence, but to his poverty. If he has been unfortunate,
and not able to secure his plunder, or honest, and has voluntarily given it up, and thus has nothing left to make a sop for Cerberus, he suffers the rigour perhaps more than the rigour of the law.
Good fortune and perseverance, in dishonesty, would have enabled him to buy indulgence.
The following contrivance would, in a measure, obviate this inconvenience :
A machine might be made, which should put in motion certain elastic rods of cane or whalebone, the number and size of which might be determined by the law : the body of the delinquent might be subjected to the strokes of these rods, and the force and rapidity with which they should be applied, might be prescribed by the Judge : thus everything which is arbitrary
might be removed.
A public officer, of more re sponsible character than the common executioner, might preside over the infliction of the punishment ; and when there were many delinquents to be
punished, his time might be saved, and the terror of the scene heightened, without increasing the actual suffering, by increasing the number of the machines, and subjecting all the offenders to punishment at the same time.
Here are some drawings of spanking machines, I have tried to attach info on the illustrations as well (as far as I was able to trace those)