The <a href="https://en.wikipedia.org/wiki/Gaillard_Cut" class="extiw" title="wikipedia:Gaillard Cut">Culebra (later Gaillard) Cut</a>, as it was in December, 1904.
1904
<a rel="nofollow" class="external text" href="http://www.czbrats.com/Builders/Goethals/contents.htm"><i>The Panama Canal</i></a>, An address to the National Geographic Society, by Colonel Goethals, February 10, 1911.