 McCay's working methods were laborious. On Gertie the Dinosaur an assistant painstakingly traced and retraced the backgrounds thousands of times. Rival animators developed a number of methods to reduce the workload and speed production to meet the increasing demand for animated films. Within a few years of Nemo's release, it became near-universal practice in animation studios to use American Earl Hurd's cel technology, combined with Canadian Raoul Barré's registration pegs, used to keep cels aligned when photographed. Hurd had patented the cel method in 1914; it saved work by allowing dynamic drawings to be drawn on one or more layers, which could be laid over a static background layer, relieving animators of the tedium of retracing static images onto drawing after drawing. McCay adopted the cel method beginning with The Sinking of the Lusitania.
