In one of a series of letters widely believed to be written by the serial killer Jack the Ripper (commonly referred to as the "Dear Boss" letter) the author makes use of the following phrase:
... I am down on whores and I shant quit ripping them till I do get buckled...
Clearly the overarching meaning of this statement is that the killer has no intent to stop committing their crimes.
My question pertains specifically to the author's use of the word "down" in this context. After consulting the relevant Wikitionary entry for the word, I'm at a loss as to what exactly the phrase "I'm down on whores" means here?