to the other two. Gauge Although they were eventually classified as locomotives along with the rest of the South African narrow-gauge locomotive fleet, they were actually constructed to gauge. Historically, the actual two-feet narrow-gauge rail spacing depended on whether or not the track was laid by a metricised country. German-built narrow-gauge lines in German South West Africa were therefore gauge, while those in South Africa, built to Imperial standards, were gauge. In practice, however, the two gauges are still being treated as one and the same by, for example, the British Military. The same applied in South Africa, as part of the British Commonwealth at the time. The difference was considered as insignificant and narrow-gauge locomotives regularly migrated between the lines laid to German standards in SWA and those laid to Imperial standards in South Africa. Service The two locomotives remained in SWA after the war. In 1920, they were both reboilered by the SAR using boilers supplied by Henschel and Son, and in the process they lost their saddle tanks. Since this modification effectively converted them to tankless tank locomotives, they were equipped with timber-bodied two-axle tenders to carry their water and additional coal. Classification A system of grouping narrow-gauge locomotives into classes was only introduced on the SAR somewhere between 1928 and 1930. At that point, the two locomotives were designated Class NG2. Disposal The Class NG2 locomotives spent their last working years on the SAR working at the Usakos workshops in SWA, until they were withdrawn from service in 1936. Engine no. NG93 was sold to the Zebediela citrus estates in northern Transvaal in 1937, where it was finally withdrawn from service by 1943. Engine no. NG94 was sold to Igusi Timbers in Rhodesia and remained in service there until c. 1961. References 2550 0-4-2ST locomotives B1 locomotives Dickson locomotives 600 mm gauge railway locomotives Railway locomotives introduced in 1897 1897 in South Africa Scrapped locomotives Freight locomotives