[The year] 1855 saw the first appearance of six handsome four-coupled passenger engines built to Mr. Sturrock’s design by Messrs. R. & W. Hawthorn, which bore Nos. 223 to 228. They were, as usual, constructed with double frames and outside bearings to all the axles, and it will be noticed in the appended illustration, Fig. 24, showing No. 223, that equalizing levers were applied to the springs of the coupled wheels, as was Messrs. Hawthorn’s Fig. 24. general practice in four-coupled engines.
The leading dimensions were as follows: leading wheels 4-ft. and coupled wheels 6-ft. 6-in. in diameter respectively ; wheelbase, from leading to driving wheels 8-ft. 3-in., from driving to trailing wheels 7-ft. 6-in., total 15-ft. 9-m. ; cylinders 16 1/2-in. by 22-in. ; boiler barrel 10-ft. long with a diameter of 4-ft., containing 160 tubes 10-ft. 5-in. long with 2-in. diameter; internal firebox 4-ft. 8-in. by 3-ft. 5-in.; heating surface: firebox no sq. ft., tubes 872 sq. ft., total heating surface 982 sq. ft. ; grate area 14-92 sq. ft. ; weight in working order about 33 tons.