The New Zealand E class locomotive comprised a single Mallet steam locomotive operated by New Zealand Railways (NZR) from 1906 until 1917. Classified as E 66 and nicknamed Pearson's Dream after its designer, it was an experimental Mallet locomotive designed to work on the Rimutaka Incline. The "E" classification was previously used by the Double Fairlie E class of 1872-75, but the classification was free as they had all been withdrawn by the time E 66 entered service. After the withdrawal of E 66, "E" was again re-used on the battery-electric E class of 1922. It was the only Mallet locomotive to operate for the NZR Origin and design The Rimutaka Incline opened in 1878, connecting Wellington with the Wairarapa region, and with the completion of the Wairarapa Line in December 1897, it provided NZR's main link to the north as the west coast route was then privately owned by the Wellington and Manawatu Railway Company (WMR). Six special Fell locomotives, the H class, worked the Incline, but after 1897, traffic increases necessitated additional motive power. Initially, two members of the B class were converted from tender locomotives into tank locomotives and reclassified as the WE class; W 192 was also transferred to assist on the Incline. These locomotives proved to be more expensive to operate and used more fuel than the H class. However, they were considered successful enough by the Chief Mechanical Engineer A. L. Beattie that he authorised his Chief Draughtsman, G. A. Pearson, to design another, more powerful locomotive to work the Incline. To meet Beattie's requirements, Pearson designed E 66 as a Mallet articulated locomotive with a wheel arrangement of 2-6-6-0T under the Whyte notation system. Its cylinders were placed at each end instead of one wheelset behind the other allowing one set to be driving forward at all times. It was a Vauclain compound, re-using materials left over from an unsuccessful experiment in the 1890s on N 27. This compounding encouraged the use of a then remarkably high boiler pressure, 200 psi, which in turn caused the use of a corrugated furnace for strength. This also provided a clear space below the boiler, allowing room for the rear power bogie. The restricted grate area of such a furnace though may have been the cause of some of the steaming problems. The locomotive also used other surplus materials, such as modified F class wheels. The