 Albion , alongside Cumming 's previous ships Caledonia and Queen and other vessels , was part of the 1845 Experimental Squadron . Cumming sailed on the first trial of 1845 that lasted from 15 July to the 20 September and was supervised by Rear Admiral Hyde Parker . The trial was part of a series that attempted to compare new methods of ship building with traditional ones . Cumming at last received promotion to Commander on 9 November 1846 . His first command was HMS Rattler , a 12 @-@ gun sloop that had been the first warship powered by a steam engine and screw propeller , that he captained from 12 February 1849 to 15 April 1851 on the west coast of Africa . Whilst in command of Rattler Cumming captured the Brazilian slave brigantine <unk> on 30 October 1849 . In 1853 Cumming married Adelaide Stuart with whom he had at least one child . 
