The construction and maintenance of a railway calls for the application of so many branches of engineering that several volumes would be required to do ample justice to a subject so comprehensive and ever-extending. To avoid attempting so wide a range, the object of the following pages has been to describe briefly some of the recognized leading features which regulate railway construction, and to assist the explanation with sketches of works selected from actual practice. Where the number of existing good examples is legion, it is somewhat difficult to make a choice for illustration, and the course adopted has been to select such samples of structures as appear best to elucidate in a simple manner the different types of work under consideration. In the drawings and diagrams many important minor details are necessarily omitted, partly to avoid complexity, but principally to leave more prominent the leading features of the particular piece of work referred to in the description. Some of the sketches of the large span bridges and large span roofs are only shown in outline; but, as their principal dimensions are given, a general idea can be obtained of their actual proportions.