186 Scientific Intelligence. 



of all ranks. At half-past two o'clock, about half flood tide, the raft, pre- 

 pared for the occasion, stationed on the Carnarvonshire side, which sup- 

 ported the chain intended to be drawn over, began to move gradually from 

 its moorings, towed by four boats, with the assistance of the tide, to the 

 centre of the Strait, between the two grand piers ; when the raft was pro- 

 perly adjusted, and brought to its ultimate situation, it was made fast to 

 several buoys, anchored in the channel for that specific purpose. The 

 whole of this arduous process was accomplished in twenty-five minutes. 

 The end of the chain, pending from the apex of the suspending pier on 

 the Carnarvonshire side, down nearly to high water mark, was then made 

 fast by bolts to that part of the chain lying on the raft, which operation 

 was completed in ten minutes. The next process was fastening the other 

 extremity of the chain (on the raft) to two immense powerful blocks, for 

 the purpose of hoisting the entire line of chain to its intended station, the 

 apex of the suspending pier, on the Anglesea side. When the blocks were 

 made secure to the chain (comprising twenty-five ton weight of iron) two 

 capstans, and also two preventive capstans, commenced working, each pro- 

 pelled by twenty-four men. To preserve an equanimity in the rotatory 

 evolutions of the two principal capstans, a fifer played several enlivening 

 tunes, to keep the men regular in their steps, for which purpose they had 

 been previously trained. The chain rose majestically, and the gratifying 

 sight was enthusiastically enjoyed by each individual present. At fifty 

 minutes after four o'clock, the final bolt was fixed, which completed the 

 whole line of chain- From the casting ofFof the raft, to the uniting of the 

 chain, took up only two hours and twenty minutes. 



This splendid specimen of British architecture will be a lasting monu- 

 ment to the discernment of the present government, for having called into 

 requisition the transcendent talents of Mr Telford, who was present on the 

 occasion. 



Upon the completion of the chain, three of the workmen had the teme- 

 rity to pass along the upper surface of the chain, which forms an inverted 

 curvature of 680 feet. The versed sine of the arch is 43 feet. 



The following is a summary account of the dimensions of the bridge : — 

 The extreme length of the chain, from the fastenings in the rocks, is about 

 1600 feet. The height of the road-way from high-water line, is 100 feet. 

 Each of the seven small piers, from high-water line to the spring of the 

 arches, is 65 feet. The span of each arch is 52 feet. Each of the two 

 suspending piers is 52 feet above the road. The road on the bridge con- 

 sists of two carriage-ways, of 12 feet each, with a footpath, of 4 feet, in 

 the centre. The carriage-roads pass through two arches, in the suspend- 

 ing piers, of the width of 9 feet, by 15 feet in height to the spring of the 

 arches. To counteract the contraction and expansion of the iron, from 

 the effect of the change of the temperature in Winter and Summer, a set 

 of rollers are placed under cast-iron saddles, on the top of the suspending 

 piers, where the chains rest. The vertical rods, an inch square, suspend- 

 ed from the chains, support the slippers for the flooring of the road- way, 

 the rods being placed 5 feet from each other. The chains, 1 6 in number, 

 contain 5 bars each ; length of the bar 9 feet 9 inches, width 3 inches by 



