The engineering work for the construction of the tunnel must have taken a long time; the soil is clay, but how such material, carried out in pocketfuls and scattered about over the airing-court, not much more than two acres in extent, can have escaped the eye of the turnkeys, the doctors, and other officials, will ever remain a mystery. If the word “_pré_,” used by Foulley in his description of each court, may be literally translated as “meadow,” implying that, the airing-courts, except where they were paved for a space immediately within the boundary fence, were covered with grass, it is quite conceivable that the scattering of the soil, skilfully carried out, would scarcely be noticeable. The other attempt in 1807 occurred on 25th September, when 500 of the prisoners, between ten and eleven at night, rushed simultaneously against the interior paling of the prison and levelled one angle of it to the ground. From forty to fifty were severely wounded by the bayonet before they were driven back; happily firearms were not used. It was after this incident, showing the feebleness of the interior paling, that the brick wall was erected in place of the outer wooden fence. A letter written in 1798, by the agent, Mr. Perrot, to the Transport Officer, Captain Woodriff, illustrates some of the difficulties encountered in this large and understaffed prison by the agent and others holding responsible posts. A rumour having reached Mr. Perrot’s ears that on a certain day an attempt was to be made by seven prisoners to escape from the south-eastern quadrangle, he had the usual count made that night, and special counts twice on the following day, but the irregularities in the response to the roll-call rendered it futile for detecting any deficiency in the numbers. To overcome the difficulty, Mr. Perrot at 5 a.m. took all his clerks, a turnkey, and a file of soldiers into that quadrangle, and had a separate muster of those confined within the separate court of each of the four caserns; he thus discovered six prisoners had escaped from the officers’ prison. How they escaped was not discovered. In one fence a pale had been removed, and probably bribery had overcome the other obstacles. Any soldier or other person about the prison who could be convicted of receiving a bribe or even treating with a prisoner on the subject of an escape was severely punished, soldiers having received 500 lashes for the offence. How necessary it was for the agent and the garrison to be at all hours prepared for such attempts is shown by the fact that in December 1808, when there were 6,000 prisoners at the Depot, a search brought to light no fewer than 700 daggers of various forms and workmanship. These had been introduced from outside, as they were evidently not of prison manufacture.