W. F. Bewley and W. Buddin 



11 



deep bricked artesian wells, shallow surface wells, brooks and ponds. 

 The position of the wells or other source of supply with regard to the 

 actual houses varies considerably, some being placed in a central position 

 surrounded by glasshouses while others are at various distances away. 

 Analyses have been made of water from wells, etc., of different types 

 and position in order to ascertain how far these factors affect its purity 

 as regards contamination with pathogenic micro-organisms. 



Experimental. 

 A reliable method of samphng was devised by filtering large volumes 

 of water through a filter prepared in the following manner, and examining 



il-~ Wire clips 



Cotton-wool 



I- Wire netting 



"""^^^^oiminir^ 



Cotton-wool 



Fig. 1. Filter. 

 A. Plan. B. Section. 



the debris collected. A piece of wire netting, eight inches square, with 

 four meshes to the inch, was cupped in the centre, making a circular 

 depression four inches in diameter and three quarters of an inch deep, 

 Fig. 1. A layer of absorbent wool about a fifth of an inch thick was 

 placed in the circular depression and held in place by another piece of 

 netting similar to the first, but having the central depression only half 

 an inch deep. The two pieces of netting were firmly fixed together at 

 the four corners by means of copper wire, the filter wrapped in brown 

 paper and steriMsed. To obtain the necessary sample, the sterile filter 

 was secured over the outlet hole of the tank when the latter was empty. 



