576

HISTORY OF ENGINEERING.

Book I.

Harecastle tunnel^ upon this canal, was constructed by James Brindley , for a distanceof 2888 yards, at a level of 197 feet from the highest summit of the hill above it. Thistunnel would only permit a 7 feet boat, with a moderate lading, to pass through it, andthen only by employing loggers to propel it, a class of men who, lying upon their backsupon the freight, pushed against the sides and top of the roof with their feet, and thusmoved the boat onwards. The tunnel is only 9 feet in width, and 12 feet in height, andoccupied nearly eleven years to complete; and to pass a boat through it occupied two hours.

In the year 1824 Mr. Telford commenced another tunnel, at a distance of 26 yards fromthat already described; its length is 2926 yards, its width 14 feet, and height 16 feet, of

Fig. 564. ELEVATION OF TOWING PATH. PLAN OF TOWING PATH.

Fig. 555.

HARECASTLE TUNNEL.

which 4 feet 9 inches is covered by the towing path, leaving 9 feet 3 inches for the passageof the boat; the path is supported by pillars, and the water flows under it. There arealtogether fifteen shafts sunk from the surface, the deepest of which is 179 feet; theywere so well set out, and the headings so accurately driven, that the whole length may beseen at one view.

The bricks were made from clay of superior quality, after being triturated by machinery ;the mortar was of Barrow* lias limestone, ground in a mill, and when set is quite im-pervious to w’ater. The first brick was laid on the 21st of February, 1825, and the last onthe 25th of November of the following year, and the whole w*as opened after not quitethree years from the commencement of the works. The total number of bricks used was8,814,000 in all, for shafts, culverts. &c. The total cost of all the works connected with

this tunnel w*as 112,681£

£

Sinking 15 shafts 9 feet diameter ----- 1,610

Driving heading through hill - 7,057

Driving cross-heading to carry off water - 470

Driving headings in coal measures to drain sand at north end - 540

Excavating body of tunnel, turning brickwork, including timber,

length 2926^ yards ------ 43,435

Expense of towing path ------ 9,600

Expense of railway, 6£ miles ----- 7,000

Expense of providing bricks, morlar, centering - 22,750

Labour upon mortar and centering - 1,537

Carriage of materials ------ 4,060

Expense of open cutting, entrances and turn-over bridges at each

end, workshops, mills, engines, pumps, damages of land fences, &c. 14.622

£112,681

River Withavn Navigation , from the city of Lincoln through Boston , to its outfall intothe sea, a distance of about 43 miles. The River Witham. from Lincoln to Boston , runsin a very crooked course, until it reaches the extensive fens of that district called Hollandon the south, and Wildmore and West Fens on the north, and then passes through the highmarshes into the great bay called Metari’s Estuarium . This river was formerly navigablefor large vessels, from its outfall at the Scalp to Boston , and from thence to Lincolnbarges and other smaller boats could float at all times of the year. In the year 1744