“_American Bridges of Suspension._--It appears from a treatise on Bridges by Mr. Thomas Pope, architect, of New York, published in that city in the year 1811, that eight chain bridges have been erected upon the catenarian principle, in different parts of America. It here deserves our particular notice, however, in any claim for priority of invention with our transatlantic friends, that the chain bridge over the Tees was known in America, as Pope quotes Hutchison’s vol. iii., and gives a description of Winch Bridge. It further appears from this work that a patent was granted by the American Government for the erection of bridges of suspension in the year 1808. Our American author also describes a bridge of this construction, which seems to have been erected about the year 1809, over the river Merrimack in the State of Massachusetts, consisting of a catenarian arch of 244 feet span. The roadway of this bridge is suspended between two abutments or towers of masonry, thirty seven feet in height, on which piers of carpentry are erected which are thirty five feet in height. Over these ten chains are suspended, each measuring 516 feet in length, their ends being sunk into deep pits on both sides of the river, where they are secured by large stones. The bridge over the Merrimack has two carriage-ways, each of fifteen feet in breadth. It is also described as having three chains which range along the sides, and four in the middle, or between the two roadways. The whole expense of this American work is estimated to have been 20,000 dollars.
“_Proposed Bridge at Runcorn._--Perhaps the most precarious and difficult problem ever presented to the consideration of the British engineer was the suggestion of some highly patriotic gentlemen of Liverpool, for constructing a bridge over the estuary of the Mersey at Runcorn Gap, about twenty miles from Liverpool. The specifications for this work provided that the span of the bridge should measure at least 1000 feet, and that its height above the surface of the water should not be less than sixty feet, so as to admit of the free navigation of this great commercial river. The idea of a bridge at Runcorn, we believe, was first conceived about the year 1813, when the demand for labour was extremely low, and a vast number of the working classes of Lancashire were thrown out of employment. A variety of designs for this bridge were procured by a select committee of the gentlemen who took an interest in this great undertaking. The plan most approved of, however, was the design of a bridge of suspension; and Mr. Telford the engineer, and Captain Brown of the Royal Navy, are understood pretty nearly to have concurred in opinion as to the practicability of such a work. Mr. Telford has reported fully on the subject, and has estimated the expense of his design at from £63,000 to £85,000, according to different modes of execution. Though as yet little advancement has been made in carrying this enterprising design into execution, yet the novelty and magnitude of an arch of 1000 feet span is a subject of so much interest that we have thought it proper in this place to mention these circumstances.