56 



and, therefore, restrain decomposition ; and this condition may- 

 be indefinitely prolonged at or below freezing point, but with 

 an elevation of temperature the liability to undergo change or 

 decomposition immediately returns. Heat above 140° destroys 

 the structure of organic poisons, while it otherwise operates 

 beneficially by producing expansion and consequent dilution 

 of the noxious matter. But under 120° it evolves gaseous 

 matter. 



In the ventilators from the sewers to the street level 

 in my opinion columns of sewer gas will be formed through 

 the various causes within the sewers which are always in opera- 

 tions — escapes from which will be determined by the tempera- 

 ture and barometric changes ; and thus the air of our streets 

 will be rendered impure by such emanations, and the body less 

 healthy, and, therefore, less capable of resisting disease poisons. 

 In the treatment of this subject I propose to consider — 

 1st. House drainage in Adelaide as proposed by the late 



Mr. Clark. 

 2nd. House drainage in Adelaide, as enforced by regula- 

 tions. 

 3rd. House drainage in Adelaide, as suggested by the 

 author. 



I. — Me. Clark's System. 



The report under date January 14, 1878, by the late Mr. 

 Clark distinctly lays down fixed law^s, viz., (1) pure air is 

 essential to healthy existence ; (2) modern instances are 

 numerous, testifying to the sanitary influence which pure water 

 and efficient drainage have upon the public health ; (3) if all 

 the filth which is produced be removed at once and completely 

 before decomposition can take place, and the malarious gases 

 are engendered, the cit)^ is in a perfect sanitary condition. 



He then states : — " The third use of the sewers is the re- 

 moval of the water supply after having served its domestic 

 purposes, and with it the excrementitious and other matter 

 which can be conveyed away in running water. To do this 

 perfectly and continuously they must be laid with an inclination 

 which shall insure a certain velocity. There must be no stoppage 

 or stagnation in the stream from the point of inlet to the outlet. 

 If these objects be attained — and they easily can be — it is evident 

 that there will be no time for decomposition to engender 

 noxious gases in the sewer." He then recommends for con- 

 sideration of the authorities that a plan of the city be made 

 with the points where drainage will be required shown on, 

 such as sinks, closets, water taps, and stack-pipes. The pos- 

 session of such a plan will enable the engineer to lay out in 



