532 PROCEEDINGS OF SECTION 11. 



" Science moves but slowly, slowly creeping on from point to 

 point" said Tennyson, so has it been with the development of the 

 water carriage system of sewerage. An investigation and study 

 of the lines along which the most important advances in sanitary 

 engineering have been made, clearly indicate the first principles 

 which govern the construction of a sanitary water carriage system 

 of sewerage. Briefly stated these principles are as follows : — 



(a) As to collection aud removal of sewage. 



1. Rapid and complete removal of sewage from dwelling 



houses and factories, and its transmission beyond the 

 limits of the populated area. 



2. Impermeability of sewage conduits. 



3. Thorough ventilation of the conduits. 



4. Exclusion of rain-water from sewage conduits. 



5. 'Adjustment of the sizes of the conduits to the quantities 



of sewage to be removed by them. 



6. Exclusion of diseased or fermenting matters from conduits. 



(b) As to disposal of sewage. 



7. Non-pollution of sources or possible sources of water 



supply. _ 



8. Non-pollution of the atmosphere. 



9. The restoration to the soil of the fertilising matters con- 



tained in the sewage. 



According to the degree in which these principles are observed 

 in practice,' so will be the measure of success, not only from a 

 sanitary point of view but from an economic 'one as well. 



Before proceeding to explain these principles and the benefits 

 to be derived from their observance, it will be necessary to have a 

 clear understanding of what is meant by the word " sewage." 



By sewage is meant the waste liquids from dwelling houses and 

 factories, and consists chiefly of the water which having been used 

 for culinary and sanitary purposes, and for processes of manufac- 

 ture, has become charged with putrescible organic and mineral 

 matters and other waste products. In quantity it is practically 

 equal to the amount of the water supply, and varies as the 

 consumption of the water varies. 



Fresh sewage is comparatively harmless, but it contains a great 

 power for evil. It will remain ft^esh long enough to enable it to 

 be got rid of completely before harm ensues, if the right means 

 be adopted. It must be set running and kept running until it is 

 properly disposed of. The miscliief of sewage is that if it does 

 not i-un, or does not run fast enough, it ferments and corrupts, and 

 corrupting breeds poisonous miasma, so that they who live in the 

 neighbourhood inhale disease at every breath. 



Thus it will be seen how very important it is to ensure the 

 removal of the sewage before putrefaction sets in. The demands 

 of the first principle must be comjjlied with. In the comparatively 



