FOE PLEASUEE AND PEOFIT. 105 



at present neglect to avail themselves of similar oppor- 

 tunities. 



In connection with the lake and fish-pass at Battleby, it will 

 be noticed that the prominent feature is the great dam ; and 

 it is evident that such a structure must be built by properly 

 qualified workmen under the direction of an expert piscicul- 

 tura-1 engineer. Dams are necessary evils in fish-culture 

 operations, and a few vords concerning them may not be out 

 of place just now, seeing that we have ons cf some importance 

 before us. Livingston Stone never made a more weighty asser- 

 tion than when he wrote : " If it is necessary to build a dam, I 

 would recommend to the inexperienced to procure, by all 

 means, the skill of an engineer or practical dam-builder who 

 understands the nature of running water, for to confine run- 

 ning waiter securely is an art in itself, and a beginner is almost 

 sure to make a mistake somewhere, fcr which in the end he will 

 pay a heavy penalty in losses. . . . Employ an experi- 

 enced man, then, to build the dain, if you must have one, and 

 tell him to make it doubly safe ; and even then, if your experi- 

 ence is like mine, you will be sorry you built it ! " The dam at 

 Battleby is built cf massive proportions from solid concrete, 

 and is of the form generally known as a " buttress " dam. It 

 goes without saying that such work must be allowed to tho- 

 roughly "set" before any water is permitted to accumulate 

 against it. But for ordinary purposes I have a liking for 

 earth daons, and, most decidedly, in the case cf small dams, 

 they are much to be preferred, the precaution absolutely neces- 

 sary in connection with them being to guard against the pre- 

 sence of rats or. other animals that may undermine your work. 

 Herr S. Jaiffe, of Osnabruck, is a great believer, also, in earth 

 dams, and I cannot do better than quote his advice in connec- 

 tion with this subject : " Before a dam is attempted, a good 

 many things have to be calculated; before all, the maximum 

 amount of storm water likely to gather after a sudden stcrm 

 or cloud-burst, and a storm-water channel, with a very full 

 allowance for this extra amount of flow has to be arranged for." 

 (I explain this fully in the chapter on the formation of ponds 



