340 PROCEEDINGS OF THE SECTIONS. 
If not so intercepted, and directed into such spaces that it cannot 
be breathed, it will at times gain such expansive strength in the 
sewer that it will force itself through water-traps and other con- 
trivances into the dwelling, to the detriment of the air therein and 
the health of the occupant. 
e occasional introduction into or outbreak of fever, epidemics, 
&e., in a town or city, although they are grievous calamities, 
generally serve one good purpose in directing a lively attention to 
é existence of any filth, to the appliances for securing cleanli- 
ness in the city, and to the suppression of noxious practices in 
the environs of the dwelling. 
SypNEy Sewers. 
The sewers, now forming the system in use in this city, were 
constructed at various periods, under different engineers, an 
consequently vary somewhat in design, but generally exhibit 
sound knowledge in the designer, and perform their functions very 
well, if we grant that these duties consist of discharging the refuse 
liquids and storm-water of the city into the harbour. 
While this is their present condition, it should be stated, 
although it is generally well known to most residents of Sydney, 
that the Government Sewers Department is engaged in the con- 
struction of a capacious intercepting sewer, into which the whole 
drainage of the northern and western slopes of the city will, when 
@ main trunk sewer, runnin generally along the bed of Shea’s 
conveyance of the storm-water that falls upon the whole surface 
as well as the sewage, and this has entailed a larger outlay to 
ai win object than is considered warrantable under more 
ideas, since it appears to modern engineers that the gutters 
and water-tables should do a portion of the work, and thereby 
obviate the inordinate cost of making a double provision for the — 
same work, 
The southern system is being constructed to receive the rain- 
water rE ae and yards only, storm-water from streets, &, 
exclu oe 
being exel 
