In the notes shown to me the observations alluding to this work in particular, as an illustration of the views you were explaining, appear to have been curtailed, and the allusions rendered somewhat less direct; but still the inference unavoidably to be drawn from them is, that the back joints, as we call them, and other defects which exist originally, or which show themselves after a time, in this rock, are not well known, and tolerably well understood and guarded against, by practical engineers, and even by our workmen. In this opinion I assure you you are mistaken. Ignorant as I may probably be myself of the science of geology, I cannot have been engaged for several years in making very extensive excavations, probably the largest hitherto made, in this particular rock, having also the opportunity of examining very old and large quarries in the same rock and close to the line, having among my assistants men not meanly acquainted with this particular branch of geology, and surrounded by workmen of considerable experience, I cannot have gone through such a study without acquiring a very intimate and practical knowledge of the structure and peculiarities of the particular mass of rock which is now in question; and I will say frankly what I feel upon this point, which is, that I ought now to possess a more thorough and practical knowledge of this particular rock and its defects, and the best mode of remedying them, than even you yourself, with your immeasurably greater scientific knowledge of rocks generally. The opinion you are said to have expressed of there being great danger of some serious accident occurring in the tunnel is, I am firmly convinced, erroneous; at all events the reason given convinces me that you have not become acquainted with the means which have been taken by me to examine and to ascertain the security of every part of the rock, to remove or to support with masonry any part not so ascertained to be secure, or with the precautions taken to prevent any such accidents as those you have imagined. And notwithstanding the heavy responsibility which rests upon me, from all which you gentlemen of science are, happily for yourselves, so free, I feel that as regards the works of the Box Tunnel everything necessary has been done to render them secure, and that the doubts and fears you have so easily raised, but which it might be more difficult again to set at rest, are entirely unfounded.