"Butt bridge," in 1904, was an unglamorous but practical steel swivel bridge across the Liffey, a little east (downstream) of the O'Connell Street bridge (then called the Carlisle bridge). When its rotatable deck pivoted parallel to the quays, it allowed ships to pass up to that central point in the city.

JH 2011

Photograph, taken from the roof of the Custom House, of Butt Bridge in the foreground, looking west to the Carlisle Bridge in the background. The bridge is closed, and ships are moored on both sides. The Loopline bridge is not visible, so the picture must have been taken before 1891. Source: www.irishtimes.com, courtesy of the National Library of Ireland.