PREFACE 



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. 



No allusion is made to the requisite strengths of the various 

 structures described, nor to the necessary dimensions of the 

 materials used in their construction, as this would necessitate 

 the introduction of a vast amount of mathematical formulae 

 which does not come under the province of the object in view, 

 and which the engineer has already at command from his train- 

 ing and works of reference. 



Neither is any mention made as to the probable cost of the 



