A DEVICE FOR COUNTING YOUNG FISH. 



By ROBERT K. ROBINvSON, 



Superintendent U. S. Fisheries Station, White Sulphur Springs, 11'. Va. 



This device is intended as a means of measuring or counting young fish of a 

 size from the fry stage up to the length of i J4 inches. The instrument is made 

 of thin brass, nickel plated, and weighs about i pound. The 

 cylindrical base is 4 inches in diameter and 4 inches high, 

 with a top or neck which tapers to a diameter oi \% inches, 

 at which point is joined an upright tube of this diameter and 

 15 inches long. The tube is enlarged at its upper end to 

 form a funnel mouth. Immediately above the base, upon 

 the sloping neck, is fastened a small metal tube, and to this 

 is attached, by means of a short piece of small rubber tubing, 

 a glass tube }i. inch in diameter which extends up to the base 

 of the funnel at the top and is held in place by wire clamps. 

 Behind the glass tube, on the main tube of the apparatus, is 

 engraved a lo-inch scale, graduated 10 points to the inch, 

 beginning at zero at the bottom, and each fifth point above 

 numbered consecutively to the top, or to 100 points. The 

 lower end of the small metal tube is set in a shield of metal, 

 which is soldered to the sloping neck of the base of the vessel, 

 this covered area of the latter being perforated to permit the 

 entrance of water into the small tube while screening out the 

 fish. Immediately below the zero point, and to the side of 

 the scale, there is a small vent or valve, which is controlled 

 by a spring lever and serves conveniently to adjust the water 

 level in the apparatus to the zero point on the scale. The 

 mode of using the apparatus may be understood by the fol- 

 lowing directions: 



Fill the measure with water until the latter appears in 

 the glass tube slightly above the zero point on the scale. By 

 pressing the upper end of the valve lever the water may be 

 allowed to escape and thus be easily adjusted to the zero 

 point. 



Count out from any given lot of fish to be measured 300 

 to 500 of average size. Put the counted fish into the measure 



as free of water as possible; this may be done by putting Measure by means of which 

 them into a quart graduate and, holding a small hand net 

 tightly over the top of the graduate, draining the water off quickly by in- 

 verting the graduate. A perforated dipper may serve in place of the hand net. 



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