 In 1834, the engine was selected for further (unsuccessful) modifications to test a newly developed rotary steam engine designed by Admiral The 10th Earl of Dundonald.At a cost of nearly £80, "Rocket"s cylinders and driving rods were removed and two of the engines were installed directly on its driving axle with a feedwater pump in between.On 22 October, of that year, an operational trial was held with disappointing results; one witness observing, that "the engine could not be made to draw a train of empty carriages".