ATKINS ON FISinVAYS. 000 



submerged, opening 12 or 1-J: inches square at the bottom of eacli pool, 

 antl midway of its widtli instead of at one side. The inlet is made 

 larger than any of the subsequent passages, so that the pools are kept 

 full. The dimensions adopted by Mr. Cail are as follows: Pools at least 

 G feet square ; bottom of first pool 4 feet below the crest of the dam ; 

 each of the subsequent pools successively IS inches lower than the one 

 that precedes it ; inlet 14 inches square; other passages 12 inches 

 square. With pools 3 feet deep the passes are nearly 2 feet under water. 

 The theor^^ of the inventor is that the water in each pool acts as a 

 cushion to the inflowing column, retarding its velocity sufficiently for 

 practical purposes. This device* has been tried at Dinsdale, and pro- 

 nounced successful with salmon. Judging merely from the plans and 

 descriptions, it does not api)ear to have any advantage over Smith's 

 and similar contrivances. Though fully satisfactory with salmon, its 

 success with alewives would be doubtful. 



7. — pike's fish-way. 



This (Plate XXIX, fig. 1, perspective view; fig. 2, ground-plan) is 

 the invention of Robert G. Pike, esq., of the board of commissioners 

 oti inland-fisheries of the State of Connecticut. It differs from any 

 yet described in having long, narr'ow galleries instead of short pools. 

 The floors are level, and the descent accomplished by easy steps of 

 3 inches each. The velocity of the current is checked by change of 

 direction and by the convergence of the sides of the galleries. For 

 the salve of economy in space and material, the galleries are built 

 side by side, without waste-space, and arranged in a sort of spiral. 

 In regard to dimensions, Mr. Pike writes as follows : 



"I propose to build fish-ways upon this plan, (for falls of 3 to S feet 

 height,) with passage-ways 2i feet wide, narrowing to 18 inches; the 

 sides to be 2 feet or 30 inches high, and the fall not less than 1 in 25 or 30. 

 The saving of material in this form of fish-way is not far from 35 per 

 cent., to say nothing of the extensive masonry and cob-work usually 

 required in long fish-waj's." 



''■In making one circuit of a fish-way of the above dimensions, the 

 water traverses 7 galleries, having a total length of 6S feet, and falls 

 over 14 steps of 3 inches each, which gives it a total fall of 3^ feet to 

 each circuit. Having reached the end of the circuit, the water i)asses 

 under the point of beginning, and pursues its course through a second 

 circuit, which is precisely like the first. Between the several floors of 

 the spiral there is thus a space of 3.} feet, of which about one foot can 

 be left open in the outer walls for the admission of light. The inner 

 galleries are lighted by smaller apertures. The comi^actness, economy, 

 and easy grade attained by this device are remarkable, and I think 

 entitle it to be considered the most valuable contribution to the science 

 of fish-ways since the invention of Smith." 



* See illustration. 

 S. Mis. 71 39 



