From a friend, my brother:

The word "jail" is from English gaol pron. jail.
 
the "g" of gem, George, gimcrack, gin, etc. sounds like "j" to 
illiterate irish people in NYC ca. 1850-1880 when slang term "g:" for 
jail evolved, "g" is the cooler (cu/laire: a dark recessed place, a 
dungeon, a jail.) probably here the "UP" refers to UP NORTH of NYC in 
Ossining, AKA SING SING.
 
68% of NYC jail population in 1868 is irish or irish american.
   
it wasn;'t any classical reference to heaven it was a saol luim (slum) 
term for JAIL (gaol.) 
 
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