168 ANIMAL LIFE UNDER WATER 



water supply is obtainable. The general 

 principle, as shown on the bottom half of 

 the plate opposite page 8, is the best. The 

 observation chamber consists of a large wooden 

 water-tight box, with a plate-glass window in 

 one side, and a lid that fits over the top. This 

 box is let into the side of a small stream, and 

 [the pond formed by holding up the water below 

 with a bank or wall. In the bottom of this 

 bank or wall there should be a six-inch pipe, so 

 that the water may be run off easily when it is 

 desired to clean or alter the pond. Given a 

 suitable position, the cost of such an arrange- 

 ment before the war was about £15 to £20. 



I have always been interested in fish life, and 

 originally built an observation pond so as to be 

 able to take photographs of fish illuminated as 

 in Nature. The results were fully described in 

 "Marvels of Fish Life," published by Cassell 

 and Co. in 1911. 



My observations gradually led to the investi- 

 gation of the destruction of fish by their natural 

 enemies, particularly in the case of the fresh- 

 water fish of our rivers and inland waters. 



Inland waters well stocked with good-sized 

 fish are rapidly becoming scarcer, and good free 



