As you ask me my opinion of the advisability of patenting your bridge, I give it you; though you will probably be the first person who will have followed such advice if you do so, and might safely patent such a novel mode of using advice.
In my opinion you cannot patent the bridge. Without detracting in the least from your merit of invention, the form has been so frequently and exactly applied that no patent could hold. The Saltash bridge now just advertised for letting is exactly on the same principle as regards form; and this is so old to my knowledge that I can claim no invention, and the use of cast iron for such purpose is also incapable of being patented. There is much that is good in your bridge, and you deserve credit, but you would find innumerable claimants to dispute, and successfully, your attempt to claim a monopoly by a patent—I myself for one. Besides, I see it published in a book.
‘May 30, 1854.
‘As to your present enquiry, I do not think that what I am doing at Saltash would be applicable in this case; but without being guilty of great presumption, I think I may say that if the same plan will not do, it is fair to assume that the same brains which concocted the plan to suit the difficulties of the Tamar might very likely find the means of overcoming those of the Severn.
If I should be able to suggest a feasible plan, and there should be found people ready to make it, I shall have the satisfaction of bridging the Severn as well as the Tamar.’
[106] It has of course been impossible to refer to the points on which Mr. Brunel was aided, in his different works, by the suggestions of his assistants; but it may be mentioned here that, as appears from one of Mr. Brunel’s letters, the plan of working under a diving-bell had been proposed by Mr. William Glennie, his assistant, before he knew that Mr. Brunel had decided to adopt it.
Mr. Brunel also mentions in another letter that the ‘very simple and effectual manner’ of applying the pneumatic apparatus, by forming the annular space round the circumference of the bottom of the cylinder, was suggested to him by Mr. Brereton, when the method of constructing the cylinder was being finally settled.
[107] In the Proceedings of the Institution of Civil Engineers, vol. xxi. 1861-2, will be found a paper by Mr. Brereton, giving a detailed description of the means employed for the construction of the central pier.
[108] Shortly after Mr. Brunel’s death some of his friends on the Board of the Cornwall Railway placed the following inscription, in raised letters, over the lard archways—I. K. BRUNEL, ENGINEER, 1859.
[109] A portion of the chains used were those which had been made for the Clifton Suspension Bridge, Mr. Brunel’s earliest design.