1206 FISHERIES OF THE UNITED STATES. [52] 



COUNTER-CURRENT FISH-WAYS. 

 THE MCDONALD FISH-WAY. 



Working model. Scale, one-twelfth. This fish- way, invented by 

 Col. Marshall McDonald, of the U. S. Fish Commission, in 18 JS 

 (patented September 24, 1878, August 5, 1879), differs in prin- 

 ciple from all previously invented or used, the water being de- 

 livered down a straight sluice-way, inclined at an angle of 30°, 

 and without acceleration of velocity. " This is accomplished 

 by compelling each particle of water to traverse a constrained 

 path, the final direction being against gravity, the retardation 

 by friction bringing the particle to rest at a lower level in the 

 way. A reference to the model will show the mechanical means 

 by which this is accomplished. The bottom of the way is hol- 

 low; each of the center openings communicates with the open- 

 ings on each side corresponding to the fourth side-intervals 

 below. A particle of water entering any one of the middle 

 openings passes under the hollow floor and returns to the sur- 

 face of way through the fourth opening below, its final direction 

 being up the slope and against gravity, which soon brings the 

 2>article to rest, when it falls again towards the middle of the 

 way, sinks into one of the center openings and traverses a 

 similar circuit ; this is repeated again and again until finally 

 the particle of water reaches the bottom of the way with no 

 greater acceleration than it received in its first circuit. It is 

 evident, then, that the maximum velocity of the current of water 

 in the fish-way can never be as great as the maximum velocity 

 of each particle of water that makes the current. The maximum 

 velocity of each individual particle is under absolute control, 

 being in proportion to the difference of level between its con- 

 secutive points of rest; we may therefore deliver the water 

 down the way with a uniform velocity which shall not exceed 

 any maximum limit desired. The fish-way is sheltered from 

 floods and floating ice or timber by being placed behind the 

 abutment of a dam. Water is brought from the dam to the 

 head of the fish-way by a conduit of boards supported by trest- 

 ling ; this conduit may, however, be built of masonry or of iron. 

 This represents Only one of a number of designs that may be 

 adopted to suit best the varying conditions of locality. To test 

 the fish- way practically, turn on, at the head, enough water to 

 keep the box full. Place young trout in the pool at the foot of 

 the fish-way, and after they have become accustomed to their 

 surroundings, they will swim readily up the way, moving as 

 quickly as the eye can follow them. For details of construction, 

 see working-drawings of design for James River fish-ways." 

 —M. McDonald. 



