RAILWAY CONSTRUCTION. 163 



primitive, the work of construction would be laborious and 

 slow. So long, however, as the workers restricted their opera- 

 tions to the solid rock, they had merely to contend against the 

 hardness of the material, as the opening or passage-way, once 

 made, required no further support or attention ; but as the wave 

 of progress swept onward, man was compelled to deviate from 

 the lines originally followed by nature, and had to form his 

 subterranean pathway through softer material, where the work- 

 ings required substantial support. The search for minerals of 

 various kinds led to the driving of long headings or galleries 

 underground, and as these had frequently to penetrate through 

 strata of a soft and yielding character, strong timber framework 

 had to be introduced to afford stability to the works, and safety 

 to the workers. For ordinary mining operations, strong rough 

 timber supports may meet all requirements, and may last until 

 the heading is worked out and abandoned ; but for subterranean 

 passages or tunnels which are intended to form permanent means 

 of communication, the strongest and most durable materials 

 must be used to protect the interior as far as possible from 

 deterioration or decay. Heavy timbering might be sufficient for 

 mere temporary purposes, but substantial masonry or brickwork 

 side walls and arching became necessary for permanent work in 

 those portions where the tunnel required artificial support. 



The first tunnels of any importance were most probably those 

 constructed for canal purposes. Many of them were of con- 

 siderable magnitude, and in some instances were from two to 

 three miles in length. They were substantially lined with 

 masonry or brickwork at all places where the tunnel passed 

 through soft material or loose rock, and from the solid nature of 

 the work, and the many years they have been in existence, they 

 thoroughly testify to the ability of the constructors. 



The introduction of railways involved the making of a large 

 number of tunnels, perhaps more so in the beginning, when it 

 was thought that the use of the locomotive would be confined 

 to very moderate gradients, and when engineers hesitated to 

 adopt the steeper inclines and sharper curves which form the 

 practice of modern times. Another element of consideration 

 also consisted in the fact that the first railways were designed 

 to connect the most populous and busiest districts, where the 

 prospects of heavy traffic would appear to warrant a large 

 outlay for works of construction. As the system spread and 



