104 FRANK C. WILSON 



A spring clamp is attached to the stopper which is operated by a 

 string so that when the apparatus is at the desired depth in the 

 water the stopper may be lifted. When the bottle is filled, the 

 string is released and the stopper is forced back into position. 

 The disadvantage of this type of sampler is the possibility of 

 contaminating the bottle and stopper near the neck while it is 

 being placed in the metal frame. It is also inconvenient to 

 manipulate two connecting lines — one for lowering the apparatus 

 and one for lifting the stopper. In addition to these points, it is 

 difficult to fasten the stoppered bottle in the metal frame. 



An inexpensive substitute for this type of sampler is sometimes 

 used for shallow water work. A glass stoppered bottle is low- 

 ered in the water by means of a string and when the desired depth 

 is reached the stopper is lifted slightly by a second string. When 

 the bottle is filled, the string is released and the stopper allowed 

 to slide back into place. The sample may then be drawn up. 



For deep-sea work a special apparatus is required. An excel- 

 lent sampler for deep-sea work is described by Matthews (1913). 

 The apparatus works on a different principle from any of the 

 samplers previously described. The container for the sample 

 consists of a strong glass cylinder which is closed at each end by 

 thick rubber washers secured by metal plates. The cylinder is 

 filled with 95 per cent alcohol before lowering in the water. The 

 alcohol is supposed to kill any bacteria that may be in the sam- 

 pler and at the same time to prevent the entrance of water before 

 the ends are opened. At the desired depth, the ends of the cyl- 

 inder are opened by dropping a messenger on the line. The alco- 

 hol, being of lower specific gravity than the water, diffuses out 

 almost instantaneously, causing an upward flow of water through 

 the cylinder, after which the second messenger is sent down to 

 close the ends of the cylinder. The sample is drawn up, and the 

 water is siphoned into sterilized bottles before they are brought 

 to the laboratory for analysis. For deep-sea water investigations 

 this apparatus is very useful, but for work on a shallow body of 

 water a less complicated apparatus may be used. 



The sampler here described is the one used by the Wisconsin 

 Geological and Natural History Survey in the work on Lake Men- 



