724 



SANITARY SCIENCE. 



7. Broken drains caused by houses settling, 

 or rats undermining the ground below them. 



8. Traps evaporated from neglect or non- 

 usage, or from their nearness to furnace-flues 

 or steam-coils. 



9. Traps that are siphoned by the pulling 

 action of other fixtures when discharged, and 

 are thus left open to the sewer. 



10. Pan water-closets, slop-sinks, and other 

 fixtures that become foul for lack of sufficient 

 flush and ventilation, and are in close rooms or 

 closets without sunlight or air. 



A well-constructed and properly laid sewer, 

 if frequently flushed, and if it has a free outlet, 

 is not productive of foul gases to any appreci- 

 able extent, especially if it is ventilated by per- 

 forated man-holes at frequent intervals. There 

 is little perceptible odor from openings in such 

 sewers, and the workmen employed in them do 

 not complain of sickness. But the case is dif- 

 ferent with sewers that are too large or have 

 not enough pitch, that are not frequently 

 flushed, or whose outlet is tide-locked, so that 

 they become clogged and are mere gasometers 

 and reservoirs of liquid filth, constantly under- 

 going decomposition and creating foul gases, 

 which are inevitably drawn up iuto our over- 

 heated houses, carrying disease and death into 

 every occupied room. In a city in central 

 New York, a quantity of benzine was accident- 

 ally discharged into a sewer, and as a result 

 every dwelling in the vicinity was filled with 

 the odor. A similar test would have a like 

 result in most large cities, both in this country 

 and abroad, and might awaken people to the 

 need both of disconnecting their houses from 

 the sewer, and of having a better quality of 

 plumbing. In many parts of New York, when 

 the tide presses against the sewer outlets, an 

 oifensive odor resembling cabbage-water is 

 everywhere perceptible. Prof. Chandler well 

 says that it would be a blessing if sewer-gas 

 stank, so that its presence would be noticeable 

 wherever it gained an entrance. Nature usually 

 raises some danger-signal to warn people of 

 the presence of evil ; but in the case of sewer- 

 gas there is often no sign to make its proximi- 

 ty known. 



Col. Waring denies the popular theory that 

 New York has unequaled advantages in being 

 swept on each side by a great river. He asserts 

 that only an insignificant portion of its sewage 

 ever crosses the bar at Sandy Hook; but the 

 main body of filth is distributed by the tide 

 from Sing Sing and Throg's Neck to Coney 

 Island, poisoning the air, strewing the shores, 

 being consumed by fishes, and contaminating 

 the air. Unless Manhattan Island can slip 

 from its moorings and float out to sea twenty 

 or thirty miles, this condition of things must 

 continue until a better one is devised. The 

 sewers of Boston and Philadelphia are no bet- 

 ter than those of New York. Col. Waring de- 

 scribes them as being " highest at the lower 

 end, lowest in the middle, biggest at the little 

 end, receiving branch sewers from below, and 



discharging at their tops ; elongated cess-pools, 

 half filled with reeking filth, peopled with rats, 

 and invaded by every tide ; huge gasometers, 

 manufacturing day and night a deadly aeriform 

 poison, ever seeking to invade the houses along 

 their course ; reservoirs of liquid filth, ever 

 oozing through the defective joints, and pol- 

 luting the very earth upon which the city 

 stands." 



His report to the National Board of Health 

 upon the sewers of Philadelphia is a startling 

 presentation of their defects. 



Size of Sewers. There is a strong tendency 

 at present in favor of reducing the size of sew- 

 ers and substituting those that are small, oval, 

 and well flushed in place of the monster cloaca 

 that have been popular with engineers and are 

 found in most of our large cities. These huge 

 tunnels soon become foul, and on account of 

 their size are rarely flushed except during un- 

 usually heavy storms. The condition of the 

 Philadelphia sewers is a striking commentary 

 upon the error of building them in such pro- 

 portions. The example of Memphis, where the 

 entire house - drainage is conveyed through 

 twelve-inch sewers, has exerted a strong influ- 

 ence and attracted much interest. In Norfolk, 

 Baltimore, Cleveland, Newport, New Orleans, 

 and other cities, smaller sewers are proposed, 

 and on economical as well as sanitary grounds 

 they are to be recommended. Sir Robert 

 Rawlinson mentions as a significant fact, show- 

 ing the great revolution in sanitary construc- 

 tion, that so late as 1850 three eminent English 

 engineers recommended for the city of London 

 that no main sewer should be of less size than 

 would allow a man to enter ; house - drains 

 were to be less not than twelve inches in 

 diameter, and a four-inch drain was thought 

 intolerable. They recommended the flat-bot- 

 tomed section as the easiest to cleanse by hand- 

 labor. Now no engineer or sanitary authority 

 would tolerate such large sewers. Yet the 

 report was accepted by European engineers 

 generally, and Paris and Brussels have sewers 

 of tunnel-like capacity. There are sewers in 

 London large enough for a cart to pass through, 

 with flat bottoms and almost level gradients. 

 The Fleet Street sewer in London is 12 feet 

 3 inches by 11 feet 7 inches; the Mill Creek 

 sewer in Philadelphia is 20 feet in diameter; 

 there is a sewer in St. Louis, nearly three miles 

 long, which is 15 feet by 20 in section ; and the 

 largest sewer in Paris is 18 feet wide and 15 

 feet high. The Parisian sewers are built large, 

 so as to be capable of constant and minute 

 inspection. They also serve to convey lines of 

 water, gas-pipes, and telegraph - wires. But 

 they are not used to receive the whole sewage 

 of the city. Since 1855 their total extent haa 

 risen from 72 to 317 miles, which is less than 

 those of New York. A large portion of the 

 house-drainage is not emptied into the sewers. 

 Notwithstanding their reported perfection, the 

 Paris sewers have not saved that city from 

 noisome exhalation?, which have caused much 



