(1.) Laying the pipes on a rigid foundation without recessing the sockets so as to give an even bearing.
(2.) Laying the pipes on foundations which afterwards yield or settle.
(3.) Laying the pipes at too great a depth without protection by concrete or otherwise to resist the pressure of the superincumbent earth, or by not sufficiently punning the filling-in, when a sudden settlement will often crack or crush a pipe.
(4.) Accidental or wilful injuries to pipes which are not noticed before the trench is filled in.
(5.) Laying the pipes at too shallow a depth without protection, when heavy traffic or a falling weight upon the surface will crush or crack a pipe.
(6.) Defective or weak pipes.[184]
The following plates give the different forms of sewerage pipes that are now manufactured in this country, in addition to those of common shapes:
BROOKE’S PATENT SUBSOIL DRAINS AND PIPE-RESTS.
