“Different in character, however, from much of the refuse of manufacturing establishments is the sewage coming from dwellings, or the sewage (in its more restricted sense of excremental matter from animal sources) which comes from our manufactories. In fact, this foul material, coming from establishments employing a large number of operators, is likely, in many cases, to have a more injurious effect upon the stream into which it is thrown than refuse from the manufacturing operations. There are, however, some branches of industry which discharge refuse material offensive and dangerous to health. Such material is discharged from tanneries, wool-pulling and hide-dressing establishments, slaughter-houses and rendering-houses. ‘Too much stress can not be laid upon the importance of preventing the discharge of such refuse.’”--(Prof. Nichols, in Fifth Annual Report of Massachusetts State Board of Health.) “The discharge of gas works is known to kill fish and destroy lower forms of animal life, which are important agents in preserving the purity of fresh water. “One would not assert that the drainage of a single house would contaminate the water of a large river like the Merrimack so as to make it unfit for domestic use, yet we must beware how we depreciate the effect of sewage matter, even in a large stream.”--(Prof. Nichols, in Fifth Annual Report of Massachusetts State Board of Health, 1875.) “With small amount of sewage the chances are favorable for the action of atmospheric influences, and particles of undecomposed material-propagating disease are rendered proportionally small, owing to the great dilution. “A minute quantity may do much harm, because it is now generally believed, that it may hold the specific thing that propagates specific diseases. “Rice water evacuations, of a cholera patient, however much diluted, still remains in liquid, although chemical test fails to detect it.