MENAI STRAITS  , a channel of the Irish

Sea, separating Anglesea from Carnarvonshire, N . Wales, extending 14 M. from Beaumaris to Abermenai, and varying in breadth from 200 yds. to 2 in . It is famous for the suspension and tubular bridges which cross it . The suspension bridge carries the Holyhead road from Bangor . Designs were prepared by T . Telford . It was begun in 1819; the first chain carried over in April 1825; the last in July of the same year, and the bridge opened to the public the 3oth of January 1826 . The cost was £120,000 . The length of the chains (from rock-fastenings) is 1715 ft., and between the piers 590 ft.; the length of the roadway between the piers is 550 ft. and the total roadway length moo ft.; the height of the roadway from the spring tide high-water level is too ft.; the breadth of the roadway including two carriage-ways and a footpath is 30 ft . The sixteen suspending chains are carried 6o ft. through rock . Their sustaining power has been calculated at 2026 tons, while the whole weight of the suspended part of the bridge is only 489 tons . During a gale a slight oscillation is noticeable on the bridge itself and from the shore .

The tubular bridge carries the

London & North Western railway . Here the channel is about 'too ft. wide, and divided in the middle by the Britannia Rock, bare at low water . The tide generally rises 20 ft., with great velocity . The principal measurements are: each abutment 176 ft.; from abutment to side tower, 230 ft.; from side tower to central tower, 46o ft.; breadth of each side tower at road-level, 32 ft.; breadth of centre tower, 45 ft . 5 in . The total length of the roadway is 1841 ft . 5 in . The Britannia tower measures at its base 62 by 523 ft.; with a total height of 230 ft . There are tot ft. between the sea at high tide and the bridge roadway bottom . The limestone used is from Penmon, 4 M. from Beaumaris . Four stone lions couchant guard the approaches to the bridge . The first tube of the tubular bridge was deposited in its place on the 9th of November 1849, the last on the 13th of September 185o .

The total cost was £621,865 . The engineer of the tubular bridge was

Robert Stephenson, who was assisted by Sir William Fairbairn and Eaton Hodgkinson .