Edington proposed the use of prison labour; he recommended that "a hulk with 200 convicts be moored near adjoining the rock, where these convicts should be employed, with proper instruments in drilling and blasting it up". He then recommended the use of ordnance; his proposal employed an iron caisson to create a dry working area, with explosives being driven into a hole. The system would ensure that the explosion would drive the force through the rock, breaking it, rather than forcing the explosive charge back through the drilled hole. He conceded that the resulting explosion might blow the caisson "to atoms, and probably be the death of some of the poor men". Early attempts to break the rock with explosives were largely unsuccessful. William Jessop was engaged by Trinity House to undertake the rock's removal; he subcontracted Ralph Walker as a consultant and James Spedding as engineer. Labourers from Trinity House undertook the physical work. It is also possible that Richard Trevithick worked on the project at some time. Jessop's proposal used a chisel, operated from a barge much as with pile driving. This method successfully reduced the height of the rock by , after which a cylindrical coffer dam (also described as being like a diving bell) was employed to allow workers' access to remove rubble. The works lasted from 1804 to 1808, and cost £42,000. Of this, Spedding's contract was £26,000. The removal of the rock caused nearby sandy shoals to disappear. John William Norie's "Sailing Directions for the River Thames", published in 1847, makes no mention of a navigational hazard in the area of the former rock.