26 PRACTICAL TEOUT CULTURE. 



the chip has traveled ten feet in one quarter of a 

 minute. Twice four are eight ; this multiplied by 

 ten, the distance traversed, will give eighty, from 

 which deduct one-fifth (1C), and we have sixty- 

 four cubic feet as the amount delivered in a 

 quarter of a minute, or two hundred and fifty-six 

 per minute. Now, as a cubic foot of water con- 

 tains about six and a quarter gallons, we multiply 

 the number of cubic feet (256) by six and a quar- 

 ter, and the result (1,599) will be the number of 

 gallons furnished per minute by the stream. The 

 accuracy of the result of this method of measure- 

 ment will depend, of course, upon the parallelism 

 of the banks and the uniformity of the depth of 

 the portion of the stream over which the chip lias 

 floated. When the water passes through a rect- 

 angular trough, the result will be found to be 

 almost absolutely correct. 



The necessity of a sufficient fall for the proper 

 arrangement of ponds, race-ways, and buildings 

 is absolute ; in fact, the maintenance of the proper 

 temperature depends greatly on the rapidity with 

 which the water flows through the ponds, a slow, 

 sluggish stream becoming rapidly heated, while 

 a rapid current may pass over a comparatively 

 long distance without the water becoming percep- 

 tibly warmer. The rapid-running mountain brook 

 is the home of the trout ; and this should be imi- 



