6 BACTERIOLOGICAL EXAMINATION OF WATER. 



felt ; it contains two metal cylinders placed one inside the 

 other ; the inner cylinder contains the sample, which is packed 

 round with wool ; the outer cylinder is much larger, and is 

 divided by partitions into sections, which are filled with 

 pounded ice. A metal lid is placed over, and securely clamped 

 to, the everted lips of both the inner and outer metal cylinders. 

 A thick layer of felt is then placed over the metal lid. The 

 wooden box is finally closed with a strong well-fitting lid, on 

 which a handle is placed. 



