“The making up of the roadway of this bridge, however, and the enlarged angle of its suspension, may be considered as limiting the span or extent of bridges of this construction to about 200 feet. The structure represented by Fig. 17 appears to possess many advantages for bridges of that modified extent, and the manner of fixing the chains is applicable to all bridges of suspension; it is likewise new, so far as we know.”
In the close of his paper Mr. Stevenson says:--
“To what extent suspension bridges may be carried is very uncertain, and he who has the temerity to advance sceptical or circumscribed views on this subject would do well to reflect upon the history of the steam-engine. When the Marquis of Worcester first proposed, by the boiling of water, to produce an effective force, no one could have conceived the incalculable advantages which have since followed its improvement by our illustrious countryman, Watt.”
A prophetic announcement, which has had its full realisation in the Suspension _Railway_ Bridge of 821 feet span at Niagara Falls, and in the still bolder design now in execution for connecting New York and Brooklyn by a steel wire suspension bridge, having a clear opening between the piers of no less than 1600 feet.
About the year 1812, Mr. Stevenson having, as adviser of the Commissioners of Northern Lighthouses, attained the position of being the most eminent Lighthouse Engineer of his day, was requested by the Admiralty to report on the practicability of erecting a lighthouse on the Wolf Rock, lying about eight miles off the Land’s End in Cornwall.
I give, from Mr. Stevenson’s “Journal,” the following curious account of the first visit he made to the rock; and it may perhaps be as well to say that all quotations made from what I have called his “Journal” are records of what he roughly noted down at the time in the form of a Diary, and are on that account perhaps all the more interesting, at least to non-professional readers.
“_14th Sept. 1813._--Waited upon Sir Robert Calder, Admiral of the port of Plymouth, on the 13th, in consequence of letters from Lord Melville relative to a vessel to carry me to the Wolf Rock.
“The Admiral accordingly appointed the ‘Orestes,’ Captain Smith, to proceed with me to the Wolf, and after landing me there, and having made my observations, Captain Smith was directed to land me at any port most convenient for me, according to the state of the weather. Captain Smith, in consequence of this order, and to suit my convenience, got the ‘Orestes’ in readiness two days sooner than he otherwise intended, and I embarked on the 14th at 2 P.M. agreeably to appointment.