I remembered the case well, for it was one in which Holmes had taken an interest on account of the peculiar ferocity of the crime and the wanton brutality which had marked all the actions of the assassin. The commutation of his death sentence had been due to some doubts as to his complete sanity, so atrocious was his conduct.

It seems strange that Dr. Watson and Sir Henry would be unconcerned about letting loose a vicious murderer on the unsuspecting population of South America, simply because his absence from Dartmoor Prison would relieve the English taxpayer from the burden of supporting him.

Conditions at Dartmoor had improved slightly since the previous century, but taxpayers' money was certainly not being wasted on frills. In Five Years' Penal Servitude By One Who Has Endured It (1877), the anonymous author describes life in Dartmoor prison at around the time of Selden's imprisonment. Sadly, he describes a merely comfortable hammock as a "luxury."

[My cell] was about as large as a second-class state room on board an emigrant ship. The cell was 7 feet long by 4 feet broad, and 8 feet high; by the side of the door was a narrow window of rough plate glass, beneath which was a small flap-table, and that had to be let down when the hammock was slung. … My attention was drawn next to the ventilation of my new abode. This was on a very primitive principle. There was a gap about 5 inches deep at the bottom of the door to let the air in. … There is one luxury a convict certainly has, and that is a good warm bed, and after a day on the bogs of Dartmoor he needs it. There is no bed in a hammock, but a man has two good blankets (three in winter), a capital rug, and two stout coarse linen sheets, with a wool or hair pillow. A great many of the prisoners never slept in such good beds when free men.

He also describes some of the men he was incarcerated with:

It has been my sad experience to have met at Dartmoor with creatures in human form who seem to be of a different species to ordinary men. They are mere brutes in mind and demons in heart. … The very worst of the characters I have been brought into contact with have generally belonged to a class known as roughs, and the worst of all are London roughs. This class appear to me to be almost irreclaimable, and not at all amenable to any ordinary moral influence. As a rule, they are as cowardly as they are brutal—their animal instincts and propensities predominate to the almost total exclusion of any intellectual or human feeling, and with them, I fear, there is but one mode of effectually dealing. Brutes they are, and as brutes only can they be punished and coerced, and that is by the Lash.

Like Watson--and many Victorians--this anonymous prisoner sees those who have committed heinous crimes as mere animals who are not entitled to human consideration.