9 2 THE CANADIAN NATURALIST. [Vol. X. 



water beetles, worms and other not very minute animals. This 

 is of course but a very partial filtration, but it is simple and within 

 the reach of all. The models of filters on a large scale capable 

 of efiectually filtering very large supplies, I now exhibit to the 

 Society. 



No. 1. Howell's Patent — filters by capillary attraction through 

 hempen cloths ; it is built in sections, so that it can easily be 

 taken asunder and cleansed. As a water-filter animal charcoal is 

 placed between the sections, and such a filter would only require 

 cleansing once a year or so. 



No. 2. Foley's Patent, is manufactured by Robert Mitchell 

 & Co. of this city. It contains sand and animal charcoal and is 

 exceedingly effective. Under the ordinary pressure it filters the 

 whole water supply of a house or public building, and is easily 

 cleansed by reversing the currents of water, without disturbing 

 the packing. 



No. 3. Crocket's Patent, is designed for large quantities, such 

 as district supplies, or "Station Filters." It is also cleansed by 

 reversing the supply, and is an efi"ective filter, applicable to 

 public purposes and large volumes of water. 



These designs show that there exist no insuperable difficulties 

 in the filtration of water on the large scale in Canada ; and such 

 filtration would remove one-half of the solid matter, and there- 

 fore would render the water supply twice as pure as it is at 

 present. 



