VI PROCEEDINGS. 



has been given during the year to the extermination of the mos- 

 quito, the purification of water by copper sulphate, and the ven- 

 tilation of sewers and plumbing, and the abolition of the main 

 trap. 



The extermination of the mosquito has been accomplished, 

 where it has been undertaken by first a campaign of education, then 

 the expenditure of considerable sums of money in destroying the 

 breeding places by draining and filling up, etc. 



The copper sulphate treatment of water has engaged the atten- 

 tion of the world, and it is apparently becoming more and more 

 evident (1) that water infected with algag can be purified by -this 

 means, and (2) that water which has been so purified is quite fit 

 for human consumption, and that no one need fear harmful effects. 



Abolition of the drain trap. The ventilation of sewers and 

 plumbing has been a burning question elsewhere, but the " abolition 

 of the house trap " has become a live question in Halifax, and con- 

 sequently may be worthy of more than passing notice. 



The regulations of the city health board require the installation 

 of a trap at or near the point where the drain leaves the house, and 

 although there has been much diversity of opinion elsewhere 

 regarding the necessity for its use, there had been no question here 

 until the master plumbers asked that the sanitary regulations be 

 amended so that the main trap could be omitted. This trap, known 

 in England as the intercepting trap, is in that country intimately 

 connected with the larger question of the ventilation of sewers and 

 drains, which has been more or less the subject of controversy since 

 the illness of King Edward, when Prince of Wales, in 1872. The 

 intercepting trap was patented by W. P. Buchan, Glasgow, about 

 1875, and, without any special investigation, was adopted by the 

 local government board and introduced into its model by-laws in 

 1877. Such official recognition caused its advantages to be taken 

 for granted, and deterred many people from investigating the ques- 

 tion for themselves. The controversy resulted in a general con- 

 census of opinion that " sewer gas must be cut off from the house," 

 and the intercepting trap was adopted with that object in view. 



Eecently many engineers engaged in municipal work have 

 favored the abolition of the trap, and their argument has been 



