in a great degree owing to my determined perseverance, that Mr. Stephenson's original conception has been successfully carried into execution, and that the elaborate series of experiments which I performed have established the true principle upon which tubular bridges should be constructed. To this early conception I make no claim; but with regard to the services which I afterwards rendered, I must leave the estimate of their merits to the unbiased judgement of the reader. The interest which the introduction and construction of the tubular bridges have created, will ensure for the third section of the work (which contains in detail the laborious experimental investigation) an attentive consideration on the part of the scientific reader. These researches, which have brought to light an entirely novel principle of construction, extended over a period of nearly two years, and from the advantages which I have enjoyed in having conducted a similar investigation some years since, I would venture to encourage the hope, that the results obtained from the experiments more immediately connected with these works, will not only increase our store of knowledge, but will contribute to the enlargement of our field of observation in those departments of physical truth which yet remain to be explored. In addition to the honour, which I feel, in having been selected by Mr. Stephenson as the fittest person to elucidate the subject and conduct the inquiry, I have pleasure in acknowledging the liberality which furnished the means for promoting the researches on a scale of such magnitude as to ensure conclusive results. With a more limited preliminary investigation, it is evident, that it would have been imprudent, on the part of the Chester and Holyhead Railway Company, to have entered upon a work involving an immense outlay of capital, and on which the opinions of the scientific and engineering world were so much divided. In conclusion, I have to express my obligations to several scientific and highly valued friends, for having read over the manuscript, and suggested alterations in the narrative, and omissions in the correspondence, which have rendered the work more concise, and I trust more acceptable to the general reader. I have further to acknowledge, that I am indebted to Mr. Tate, of Battersea, for the mathematical analyses, and for the interesting and valuable deductions and formula, which will be found at the close of the experiments. Manchester, June 1st, 1849. junction with Mr. Stephenson.... Precautions relative to the construction of the large tube.......... |