Complex sentence: The first major competitor to the LIRR, the South Side Railroad, was incorporated March 23,1860 to build from Brooklyn to Islip; an 1867 supplement to its charter authorized an extension to East Hampton.
Split into simpler sentences: The first major competitor to the LIRR, the South Side Railroad, was incorporated on March 23,1860 to build from Brooklyn to Islip. A 1867 supplement to its charter authorized an extension to East Hampton.