A compound <a href="https://en.wikipedia.org/wiki/bridge_bearing" class="extiw" title="w:bridge bearing">bridge bearing</a> consisting of a pivot to accommodate flexing of the bridge, sitting on top of a set of rollers to accomodate thermal expansion.  Built in 1901 according to <a rel="nofollow" class="external text" href="https://bridgehunter.com/49033">bridgehunter.com</a>.
<a href="//commons.wikimedia.org/wiki/User:Douglas_W._Jones" title="User:Douglas W. Jones">Douglas W. Jones</a>
<span class="int-own-work" lang="en">Own work</span>