The oldest surviving Watt engine is Old Bess of 1777, now in the Science Museum, London. The oldest working engine in the world is the Smethwick Engine, brought into service in May 1779 and now at Thinktank in Birmingham (formerly at the now defunct Museum of Science and Industry, Birmingham). The oldest still in its original engine house and still capable of doing the job for which it was installed is the 1812 Boulton and Watt engine at the Crofton Pumping Station in Wiltshire. This was used to pump water for the Kennet and Avon Canal ; on certain weekends throughout the year the modern pumps are switched off and the two steam engines at Crofton still perform this function. The oldest extant rotative steam engine, the Whitbread Engine (from 1785, the third rotative engine ever built), is located in the Powerhouse Museum in Sydney, Australia. A Boulton-Watt engine of 1788 may be found in the Science Museum, London, while an 1817 blowing engine, formerly used at the Netherton ironworks of M W Grazebrook now decorates Dartmouth Circus, a traffic island at the start of the A38(M) motorway in Birmingham.