A Memoir on Suspension Bridges, Comprising the History of Their Origin and Progress, and of Their Application to Civil and Military Purposes; With Descriptions of Some of the Most Important Bridges

The significant expansion that has been granted over the past ten years to suspension bridges, and the influence that they have gained on public attention, began to turn them into an object of common, as well as professional interest, that the lack of something seems to begin to be felt in a methodological treatise about them. Except for a very short work by Mr. Gumming and the account of Mr. Sag's erecting the Menai Bridge, we have no book dedicated exclusively to suspension bridges. Therefore, the author's goal in the following pages was to collect in one volume everything that he could find interesting and useful about suspension bridges; namely, first, to draw up a related account of the History of Suspension Bridges, followed by a description of the most important works of this class. Secondly, to draw conclusions from the practice of outstanding engineers, useful for those who do not have the opportunity to gain practical knowledge about suspension bridges; and to apply to this branch of mechanical engineering the rules that have been established by long practice in other departments of mechanical engineering. As for those few opinions and rules that come from the Author himself, since they do not have an established authority to support them, they will certainly be perceived with doubt and will be seriously considered. The method that he used in forming the rules was to establish a certain method of calculation based on experiments and on the obtained principles of strength of materials; and then modify the formula constructed in this way until its results correspond to the proportions accepted in practice in the best existing examples of suspension bridges. This method is perhaps not the most scientific, but it is sufficient for practical purposes, because the purpose of the rules in practical construction is to find results for new cases proportional to those that time has noted as sufficient in previous practice. Therefore, only experience can determine how effective these rules are; and if in the course of the trial they turn out to be so, the goal of the Author will be achieved.