From the Hibernian Journal; or, Chronicle of Liberty, 16 July 1784:
“Yesterday in the afternoon, a number of the prisoners, confined in the New Gaol, found means to break into the sewer that communicates from the prison to the Bradogue River, or water course that falls into the Liffey at Ormond Quay; several of them have been re-taken and conducted back to their old lodging, but better secured. About sixteen it is thought are escaped; a guard is positioned at the mouths of the Bradogue, and at the different grates and necessaries in Pill Lane through which this water course runs as it is supposed several of them are still concealed within.”
The New Gaol would have been Newgate Prison situate at ‘Little Green’ beside Green Street Courthouse.
The Bradogue meandered around a bit, flowing underground from Grangegorman to North King Street and Green Street before reaching the quays. Its primary outfall was at Ormond Quay (below), but according to a news report in the Dublin Evening Mail of 26 June 1857, a tributary flowed under the Four Courts, re-emerging at Arran Quay.
The 18th century drainage system must have been rudimentary, and the stench faced by the escapees appalling.
Could some or all of the sixteen prisoners who failed to emerge at Ormond Quay have expired under the Four Courts then in the course of construction, thus contributing to its very persistent drainage problems?
More digging needed to find out!