ELEVENTH ANNUAL YEAR BOOK— PART XI 



721 



used in making official tests, and the cheaper balances on the market 

 cost from $10 to $35 — an expense beyond the reach of the mass of con- 

 sumers who should profit by practical seed tests. 



The Balance — A simple, efficient balance can be made by any boy or 

 girl at all familiar with the use of a few common tools. 



The balance consists of a hexagonal, or six-sided, pencil notched as 

 nearly as possible in the center and half way through the lead. Make 

 a rather wide V-shaped notch. Half of a similar pencil is notched likewise 

 at its center, care being taken that the angle at the apex or "bottom" of 

 the notch is made narrow, straight, and smooth. At this point the bal- 



Fig. 13. — A simple balance used in making- the puritv test of seeds- -i Siv 

 sided pencil, full length, and a half-length pencil bound to the Ions pencH 

 by rubber bands; c, shallow holes near the ends of the long pencil -d, Refer- 

 ence mark common to both pencils at a convenient point on the line where 

 they meet e, trays for holding the seed and the weights, the upper one 

 fnn°3i\ n ^ the Un ? e + r v, S1 2 e i f ' bluntly pointed end of the wire adapted to fit 

 loosely in one of the holes (c) ;g, wire bent beneath the tray to hold it in 

 position; h, piece of gummed paperholling the wire to the tray; 1, hole at 

 proper distance from the center of the tray where the wire pierces it; j, 

 thin Piece of board holding the parts of the balance in position; k, the 

 block of wood holding the knife handle at proper level; 1, darning needle 

 serving as a pointer as the pencils oscillate in weighing; m, pin marking- 

 the position of the head of the needle when the trays are properly bal- 

 anced before and at the close of weighing; n, "rider," or wire staple so 

 placed as to balance the trays when empty; o, series of selected BB shots 

 used as weights; whole ones are flattened to prevent rolling; others are 

 cut into halves, quarters, eighths, and sixteenths, and selected with ref- 

 erence to the equality of their weig-hts. 

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