sentences:  This engine survived in a derelict form in the St Nicholas works yard until the 1920s before being scrapped.Three engines of this early design with wrought iron boilers were produced and exhibited at the RASE in the late 1840s.Following this development was rapid and in only five years by 1851 the design of portable engines had matured into a form that was to remain unaltered for the rest of the steam era.