In the printing process, “type” was a small wood block topped by a raised letter or character.  The types were arranged to spell desired words and format the text, and then locked in place before ink was applied to print pages from it.  When the types spilled or were otherwise arranged indiscriminately, it was called “pie” or “pi”—derived from the word “pied,” meaning having various patches of color.  By their comments, Curtis and Brooks were saying that slavery (the “type”) had been thrown into chaos and would not survive the war.  Brooks was also the founder and editor-in-chief of the New York Daily Express, so the phrase came naturally to him, as to Harper’s Weekly editor Curtis.  In the nineteenth century, the newspaper was the main form of mass communication and many people owned or were familiar with personal printing machines, so the use of such printing jargon would be similar to using a computer metaphor today.