TRANSACTIONS OF SECTION G. 795 



FRIDAY, SEPTEMBER 7. 



The following Papers were read : — 



1. The Barnj Boclcs} Bij John Wolfe Baret, M.Inst.C.E. 



The Bai-ry Docks, which are now approaching completion, are situated ou the 

 north shore of the Bristol Channel about 7 miles westward of Cardiff. The 

 site is between Barry Island and the mainland, and the approaches from the sea 

 are very easy. Good anchorage exists eastward of the docks between Barry Island 

 and Sully Island. The docks are, as is the case with other docks on the Bristol 

 Channel, tidal, and thus can only be approached for a few hours at high water. 

 The range of tide in the Bristol Channel is large : at Barry there is a range of 

 36 feet at ordinary springs and of 19| feet at ordinary neaps. There is a depth of 

 25 feet of water at low water of spring tides within 700 yards of the entrance 

 gates of the Barry Docks. The main object of the Barry Docks is for the shipment 

 of South Wales coal, but it is expected that a considerable import trade will also 

 be developed. About 11 millions of tons of coals were shipped at the neighbouring 

 ports of Cardiff and Penarth during the past year. The Barry Docks are connected 

 with the coal-fields by new railways about 27 miles in length which are nearly 

 finished. They have easy gradients, which, on the main line, are not steeper than 

 1 in 400 against the load. The entrance of the docks is on the east side of Barry 

 Island, which protects it from westerly and south-westerly winds. Against other 

 winds the entrance is protected by two breakwaters composed of rubble protected 

 by 6-ton blocks of stone on the sea-slope. The waterway between the break- 

 waters is 350 feet and the entrance is 485 yards within the breakwater heads. A 

 channel of that length is to be dredged to the entrance. The entrance is 80 feet 

 wide and has a pair of wrought-iron gates which will be opened and closed by 

 direct acting hydraulic cylinders ; it gives access to the basin, which is 600 feet 

 long and 500 feet wide, having an area of 7 acres. Beyond the basin is the dock, 

 which is 3,400 feet long and 1,100 feet wide. This width is divided at the western 

 end of the dock into two arms by a projecting mole. The water area of the dock 

 is about 70 acres. The basin and dock are connected by a passage, which, like the 

 entrance, is 80 feet wide, and has a pair of wrought-iron gates. The basin will 

 be used as a lock, and the water in it will be adjusted to meet the rising tide each 

 day, so that vessels may leave the basin before high water, and, similarly, vessels 

 may enter the basin for some little time after high water. A floating caisson of 

 wrought iron has been provided, which wiU fit against any of the faces of the 

 entrance or passage in case of necessity. A low-water lock westward of the basin 

 is contemplated. A graving dock, 700 feet long and 100 feet wide, is being made 

 at the north-east corner of the dock. Eastward of this is the timber pond of 

 24 acres, approached from the dock by a short canal. The total area of water in 

 the dock, basin, and timber pond is upwards of 100 acres. The depth of water at 

 the entrance is 38 feet at high-water spring tides, and 29 feet at high-water neap 

 tides. The following list gives the levels of various parts of the dock and of the 

 tides above a datum line 50 feet beneath Ordnance datum : — 



Above Datum 



Feet 



Ordnance datum . . . 50'00 



High water — ordinary sjtring tides . . 69'70 



Low water „ „ .•.••. 3360 



High water — ordinary neap tides 61'30 



Low water „ „ 41'70 



Mean sea-level at Barry ........ 51'60 



Entrance channel 28"00 



Sill of entrance 32-00- 



Sill of passage 3200- 



' Printed in extenso in the Railway News, Sept. 15, 1888. 



- The sills being in the form of an invert, at the middle point there is three feet 

 more water than the nominal level above given. 



