78 



TUNNKI.IM; 



through rock, only a masonry portal is required, t.> give a finish 

 to the work. Often the engineer indulges himself in an elabo- 

 rate architectural design for the portal masonry. There is 

 danger of carrying such designs too far for good taste unless 

 care is employed ; and on this matter the writer can do no better 

 than to quote the remarks of the late Mr. Frederick W. Simms 

 in his well-known " Practical Tunneling " : 



" The designs for such constructions should be massive to be suitable as 

 approaches to works presenting the appearance of gloom, solidity, and strength. 

 A light and highly decorated structure, however elegant and well adapted for 

 other purposes, would be very unsuitable in such a situation ; it is plainness 

 combined with boldness, and massiveness without heaviness, that in a tunnel 

 entrance constitutes elegance, and, at the same time, is the most economical." 



Fig. 49 is an engraving from a photograph of the east portal 

 of the Hoosac tunnel, which is an especially good design. 



TABLE II. 

 Showing Thickness of Masonry Lining for Tunnels through Soft Ground. 



TABLE HI. 



Showing Thickness of Masonry Lining for Side Tunnels through 

 Soft Ground. 



