356 



THE MWOCHOED 



150 cm long and 12 cm in breadth and height. The long sides ma 

 have a few circular apertures (a, a, in the figure), these, howevei 

 are not essential ; the thickness of the long sides need only b 

 about 12 mm , but the short sides must have a thickness of at leas 

 20 mm . The f our W alls must be made of a hard wood, but the to 

 board should be soft and as thin as possible; a veneer of pine woo. 

 about 2 mm thick is the best, but any other small board, not quit 

 so thin, will serve for the purpose. Two triangular bridges, I 



FIG. 214 (an. proj.l real size). 



made of hard wood, each 12 cm long, 2 cm broad, and 2 cm high, th 

 cross section forming a right-angled triangle, are glued to 1 

 sounding-box, so as to turn their vertical sides to one another, a i 

 the slanting sides towards the ends of the box, the distance betw( i 

 the vertical sides being exactly 120 cm . If the student can o: 

 afford a smaller monochord, let it have a length of 80 cm , with 6< J 

 distance between the bridges. Tsvo iron pins, S S, are fi: ;l 

 somewhat aslant into one of the short sides ; wood- screws, ft i 

 which the heads are removed, will serve for these pins ; they ' 

 screwed in with the help of a hand-vice. The pins must be 

 from one another, and each 3 cm from the edge on either side. ' 

 wires which are to be stretched upon the monochord are attac i 

 to these pins by loops. Two shorter pins, s s, are fixed similarly 

 the other end of the monochord. They are made of iron wire, 

 thick, and 6 or 8 cm long ; one end is made into a point, and a sc * 

 cut up to 3 or 4 cm from the point; cross holes are also dri >! 

 through each pin, one hole l mm wide, at a distance of 3 cm from ' 

 top of each pin, and another, 2 or 3 mm wide, l cra from the 

 Narrow holes for the pins must be bored in the strong side of ' 

 box, so as to require considerable force while turning them in, u; g 



