As Chicago looks back on 150 years since the Great Chicago Fire, some of the city’s oldest organizations are reflecting on their history from that fateful day.Our firm, Sidley Austin, was in its infancy when the fire destroyed our first offices in the Marine Bank Building on Oct. 9, 1871. Before the building burned down, Sidley law clerk Charles Towne rushed back into the office to salvage the firm’s ledger, daily journal, several abstracts and a desk blotting pad.The firm’s ledger entry from the …