Walter H. Richards, Engineer Sewer Department, New London, Conn., writes:

"After reading the discussion recently published in The Engineering RECORD regarding the propriety of dispensing with a trap between the house and the main sewer, it appears that a plain statement of the whole question is desirable. It is well known that a current of air through all sewers is desirable, and is conceded by all to be necessary in the house pipes. A more complete ventilation of the street sewers can be secured by omitting the trap and ventilating through the house. A more complete ventilation of the house pipes can be secured with the trap and fresh-air inlet. A partial ventilation of the street sewers may be obtained by perforated manhole covers, and, if the sewers are reasonably well built and flushed, this without offense or danger to the community.

"In some cases, and possibly in all cases, if plumbing and traps were perfect and could be kept so, the trap on the main drain could be omitted without danger arising from the fact that by so doing all houses on a line of sewer are connected together. The question is then a practical one. Can the house plumbing be always perfect ? With the most careful planning traps sometimes syphon or the water in them evaporates because of non-use of fixture, and with the most thorough inspection plumbing is sometimes defective or becomes so after inspection. A thoroughly constructed system of sewers may suffer from neglect after a few years I think that the advantage of cutting off each building from the main sewer and adjoining buildings and confining any danger to the sewer air and disease germs in the building itself, more than compensates for a more thorough ventilation of the main sewers or for the slight saving in expense effected by omitting the trap."