'Amongst the most conspicuous exhibits at the recent conversazione at the Institution of Civil Engineers were a set of beautifully finished miniature yacht engines constructed by Messrs. John and Henry Gwynne of the Hammersmith Iron Works, Hammersmith… The yacht to which they belong has been built by Messrs. Forrest and Son, of Limehouse, from the designs of Mr. Mackrow, N.A., for Mr. H. H. Henfield, and its principal dimensions are as follows: length, 40 ft.; beam, 6 ft.; and draught 2 ft…. The machinery, which, as we have stated, has been constructed by Messrs. John and Henry Gwynne, consists of two pairs of engines placed in an inclined position… The arrangement is very compact, the engines occupying a space of 2 ft. by 2 ft. only. The cylinders are 3.5 in. in diameter by 3.5 in. stroke, and are intended to run at a speed of 550 revolutions per minute, and indicate 23 horsepower. Each pair of engines drives a Griffiths propeller, 20 in. in diameter, with a 3 ft. 6 in. pitch… Steam is supplied to the engines by a vertical tube boiler, 3 ft. in diameter by 5 ft. 8 in. high, worked at 80 lb. per square inch.'