The flat marsh by the Boilers Yards is well adapted for this establishment, but as the ground beyond is high for some distance we propose the canal to be 124 feet only at water surface for 1000 yards from the locks, and to be lined with a stone wall on each side, so that this space will, in fact, be also a dock. Afterwards the marsh widens, and here is a favourable place for another entrance basin and dock, if necessary. From this point we propose to continue the canal with sloping banks, the bottom to be four feet under the level of the old dock sill, and 163 feet in width at the surface of the water, which will be twenty-two feet in depth.
Mr. Stevensonâ€™s last visit was made in 1818, on a voyage in the Northern Lighthouse tender, on which occasion he was favoured with a smooth sea and a low tide, and enabled to make a thorough inspection of the rock. It is important and interesting to record that this examination strongly impressed him with the ultimate insecurity of the structure, as appears from the following almost prophetic extract from his Journal:â€”
To this quarter my attention, with that of Mr. Nimmo, Civil Engineer, had been professionally directed in the course of last month. In our preambulatory survey we were accompanied by Sir John Tobin and William Laird, Esq., of Liverpool, along the Cheshire shore and its connecting sandbanks between Wallasey Pool in the Mersey, and Dalpool in the river Dee.