FISH HATCHING ON A MODEST SCALE 417 



Now, what are the essential requisites of a hatch- 

 ery ? Obviously land and water, the first if possible 

 conveniently close to the dwelling of the prospective 

 hatchery manager, and the second ample. There are 

 few estates, we imagine, where a combination of circum- 

 stances of this kind will not be found. For the site 

 itself, any gently sloping plot of ground upon which 

 a wooden house, 20 ft. square, can be erected will 

 do. If the subsoil is porous so much the better, but 

 if not, a gravel foundation can easily be provided. The 

 water supply is a more important consideration. It 

 must be ample, pure, and not liable to the slightest risk 

 of interruption, for any cessation of the flow at a critical 

 juncture would be disastrous. For these reasons the 

 water supply available will determine the site. 



If it is impossible to secure, as has been secured at 

 Luss, with the kind permission of the proprietor of the 

 estate, connection with an existing domestic water 

 supply, then a stream must be looked for where a 

 sufficient head of water can be obtained. At Luss, 

 delivery is made by a \ in. lead pipe, but the head of 

 water in each case will determine the diameter of the 

 pipe necessary to deliver the quantity of water requisite. 

 This, roughly speaking, must be sufficient to give to 

 each hatching box a complete interchange of water 

 every three minutes. In a convenient stream, then, a 

 natural pool must be looked for giving a fall of at least 

 30 ft. to the proposed hatchery. If, however, no such 



pool can be found, a small dam can easily and cheaply 

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