Complex sentence: A newel is the upright post about which the steps of a circular staircase wind; hence, in stairs having straight flights, the principal post at the foot of a staircase, or the secondary ones at the landings.
Split into simpler sentences: A newel is the upright post about which the steps of a circular staircase wind. In stairs having straight flights, it is the principal post at the foot of a staircase, or the secondary ones at the landings.