The locomotives later grouped together in the class E-1 were a total of ten Camelback consolidations that the Delaware & Hudson procured in 1898 and 1899 for burning loose anthracite coal. Three were created by rebuilding a 4-4-0 and two 2-6-0. Seven others were newly built by Dickson and initially designated class U-II before becoming class E-1a.

The Wootten firebox already created a grate area of 80.3 square feet. In addition to the direct radiant area of 170 square feet, it contained a further 104 square feet in so-called “water bars”. One example of the class was built as a compound locomotive with comparatively large cylinders with a diameter of 23 and 34 inches. It was later simpled and scrapped along with its E-1 and E-1a class sisters between 1927 and 1928.