John Smeaton, the engineer charged with the construction of the magnificent Bute 
Ship Dock. 
' December 9th .—After breakfast went with Mr. Smeaton and Mr. Blews, the 
iocal superintendent of construction, to examine the new dock and harbor. This 
is perhaps the most extensive work, with the exception of the Duke of Bridge- 
water's canal, ever undertaken and finished by one individual. This improve¬ 
ment has been made by the Marquis of Bute, at his sole expense, at a cost of 
nearly .£300,000. The location was chosen by Mr. Telford, and the design and 
execution were entrusted to Mr. Cubitt. It seems that the proper precautions, how¬ 
ever, were not taken effectually to secure the foundations for the massive lock, which, 
in consequence of the pressure of the water, and the defect already mentioned, threat¬ 
ened to give way. As the water had been drawn off, and the repairs were being 
made, the whole of the forebay having been taken up, it afforded me a fair oppor¬ 
tunity of examining it to advantage, and seeing its internal structure* Captain 
Smythe politely furnished me with the plans of the work, the map of the site, 
and chart of the exterior harbor. This improvement comprises a ship canal 4,000 
feet long and 200 feet wide, with massive quay walls on either side, coped with 
blocks of chiselled granite. The canal or basin, for 1,500 feet in length, is calcu¬ 
lated for 19 feet depth of water, 1,200 feet for 13 feet depth, and the remainder 
shallows to 9 feet. The basin is supplied with water by a navigable feeder from th© 
Glamorganshire canal, or rather from the river Taaf. When it rises to 19 feet 
above the mitre-sill of the forebay, it is wasted over a weir into a large artificial 
pond, from whence the excess is discharged into the tide basin. This surplus wa¬ 
ter serves to keep the tide basin free from silt; by being admitted through a sluice 
over a fall of nearly 20 feet at half ebb, its velocity removes the sediment which had 
been deposited by the previous flood tide. The exit from the canal is through a 
lock 156 feet long by 36 feet wide, (through which a ship of 1200 tons burden, 
laden with timber, was passed the day the dock was opened,) into a tide basin, ca¬ 
pable of holding 3,000 tons of shipping, shut in by a tide gate 45 feet wide, which 
is opened at 3£ hours’ flood, when the tide outside rises to the height of the water 
within, and vessels pass out to sea through a channel which has been excavated 
in the mud, half a mile long and 150 feet wide, stretching from north to souths 
and as the winds prevail in that direction, vessels are generally enabled to hoist 
sail in the tide basin and put out directly to sea ; and in like manner they may 
frequently sail into the basin without furling canvass or dropping anchor. Buoys 
mark the channel on either side, by means of which vessels may warp in and out. 
The masonry is all of the best granite, and built in the most solid manner ; all the 
facings of the lock and tide basin, and the copings throughout being cut work, and 
every portion of the structure exposed to the action of water being laid in hydrau-' 
lie mortar. The stone from which this lime is obtained belongs to the Lias, and 
is brought from Aberthan, in Glamorganshire, and is found in rolled masses on 
the beach, having been separated from the clay with which it is enveloped when 
in situ < It is burnt and slacked like fat lime , and is mixed in the proportion of 
two lime and one sand. The other limes (the Dorking for instance) is mixed one 
