52 ' FISH CULTUEE. 



before it reaches the hatching trays. Let the re- 

 servoir which contains the water be enamelled, in 

 the same way that saucepans are ; and as water 

 passes through this tray or reservoir it will pass 

 over surfaces many degrees cooler than the air, which 

 cannot but have the effect of cooling the water. 

 The ice can easily be renewed from time to time, 

 and drippage, &e., be provided for. This plan has 

 occurred to me by the desire which I had to be 

 able to cool the water in some reasonable and easy 

 manner during the past spring, when I was losing 

 large quantities of greyling ova and fry from thai 

 high temperature of the water. 



I now proceed to describe the best kind of stream 

 appara.tus. 



In dealing with streams, those should be selected 

 in preference where the water supply comes from a 

 cool, clear spring, as near to the spring-head being 

 chosen as can be conveniently done. A reservoir 

 should be made, so as to dam the stream up to the 

 highest possible level — an open cut being left at 

 the down stream end to allow the water to run 

 through : a zinc trough, or shoot, is fixed in this 

 aperture to deliver the water. If the reader will 

 consult the engraving at p. 53, which represents 

 a pQrtion .of an apparatus I designed some time 



