Of course, different places have different prisons. But Naveenian culture is drawn from British, French, and American culture of the day, we can limit our research to those countries.
The short answer is that prisons were AWFUL. Like rats-eating-you-alive awful. No wonder Europeans had to devise such spectacular ways of dismembering and killing people--what's the point of capital punishment if it isn't any worse than imprisonment?
Peter Frost has an intersting post on the history of imprionment and execution in Europe, Making Europeans kinder, gentler.
"When the Roman Empire collapsed in the 5th century, so did its system of retributive justice... In 511, the bishops of France greatly extended the right of sanctuary. If a man committed murder, he could now ask for and receive sanctuary in any holy place.
The new barbarian rulers also disliked the death penalty... every adult male had a right to use violence and to kill, if need be. This right was of course reciprocal. If you killed a man, his death could be avenged by his brothers and other male kinsmen.
As the barbarian kingdoms developed... steps were taken to limit male violence... The punishment for murder was thus monetized. If you killed a boy under 10, you paid 24,000 denars. Killing a free pregnant woman would cost a bit more: 28,000 denars... Capital punishment existed only for the murder of the king, for whom there was no wergild, or in the case of a slave killing a free man.
Thus, for a long period, murder was normally a personal matter to be settled by the victim’s family, through vengeance or a cash settlement. This situation began to change in the 12th century... The State no longer saw itself as an honest broker for violent disputes that did not challenge its existence. Jurists were now arguing that the king must punish the wicked to ensure that the good may live in peace...
From the 12th to 17th centuries, capital punishment became steadily more prevalent. We see this in an increasing willingness to use it not only for murder but also for other crimes (rape, abortion, infanticide, lèse majesté, theft, counterfeiting, etc.). We also see this in the use of ‘exemplary’ punishment: drawing and quartering, breaking on the wheel, and burning.
Then, after the 17th century, the war on murder began to go into reverse... In England, the homicide rate fell by over a hundred-fold between 1300 and 1900."
By Lyta and Jasper's time, serious movements were afoot to reform the prisons and make them less horrible, but they were still wretched. The Enlightenment concern for the rights of the accused can be seen in the American Bill of Rights: "excessive bail shall not be required, nor excessive fines imposed, nor cruel and unusual punishments inflicted," and in the principle of Innocent until Proven Guilty, providing for a justice system which differed significantly from the torture-them-into-confession systems which formerly prevailed.
Some more information on prisons in colonial America: Cruel and Unusual: Prisons and Prison Reform, by Jack lynch.
"Early American prisons were not conceived as houses of punishment. In English and American law, political prisoners and high-ranking prisoners of war were occasionally incarcerated, but few common criminals could expect such treatment. Almost the only time commoners were locked away was while awaiting trial—once a verdict was delivered, they were punished on the spot or released...
In England... between 1688 and 1815, the number of capital crimes rose from about fifty to more than two hundred. The theft of a silk handkerchief or a pocket watch might lead to execution. ...but there were ways to escape a sentence to the gallows. English courts could show mercy by transporting convicts first to North America, then, after independence, to Australia, for sale as servants. [Avery's note: 'servant' here is a fancy word for 'slave'.] The medieval "benefit of clergy" allowed priests to avoid the harsh penalties associated with the secular courts;
...in North America, and in the years after the Revolution... State after state began reducing the number of death-penalty offenses: in 1786, for instance, Pennsylvania eliminated the death penalty for robbery, burglary, and sodomy. ... The death penalty, they said, was a distinctly monarchical punishment; reformation, on the contrary, was compatible with republican ideals. To resist the death penalty, then, was a political gesture...
Being incarcerated even briefly could be tantamount to execution. Corruption was rampant; prisoners were expected to bribe their keepers for minimally adequate treatment, and those without money were often allowed to die of neglect. The buildings, too, could prove fatal... Hygiene was appalling—open sewers often ran through the facilities—and rarely were there fresh provisions or clean water.
Dangerous settings like these led to calls for more humane houses of detention... [Unfortunately,]Prisons quickly became overcrowded, expenses mounted, and taxpayers were unwilling to make convicts' lives more comfortable. High recidivism led many to question whether reformation was possible after all. Worse still, many of the lessons learned in developing an efficient system of incarceration were applied to chattel slaves in the South, who were subjected to the same kind of surveillance and control that jailers had learned to use on criminals: the two systems reinforced each other."