 "Pylades" is what is known as "composite" built.Soon after the building of ships with iron was commenced, this composite system of construction was adopted in the British merchant service, and some very fast and celebrated vessels were thus constructed.The iron framing, with wooden skin planking, admitted of considerable strength being obtained, and the possibility of sheathing the bottom with metal in order to avoid fouling, appeared to be another advantage in favor of the composite system.