THE HOMEMADE ORCHESTRA 331 



reed or membrane. In the clarinet, the player blows upon a 

 thin elastic strip that lies over a slot (Fig. 169). The air pressure 

 depresses this strip and closes the opening. But the moment 

 the air current stops because the slot is closed, the springy 

 tongue flies up again, opens the slot, and the current flows 

 once more. This process is rapidly repeated, so the successive 

 puffs of air caused by the rapidly vibrating tongue set in corre- 

 sponding motion the air column within the body of the instrument. 

 Nearly every country lad has made a similar reed instrument. 

 He takes a hollow stalk like an oat straw or the leaf stalk of 

 squash or pumpkin, and cuts a slanting slash in it near the node 

 or closed end. He cuts off the other end so as to leave the crude 

 instrument 6 or 8 inches long (see Fig. 170). Then he sticks the 

 slot end in his mouth, covering the reed entirely, and blows to 

 produce the note, which may 

 be a squawk rather than a 

 musical sound. It may be 

 necessary to shorten the FlG - 170 A squawker made from an 



i ., , . oat straw, 



instrument a bit at a time 



until just the proper length is found that will give the best 

 result. 



Just as with the string, other things being equal, the shorter 

 the string, the higher the pitch of the note emitted, so with 

 the vibrating air column, the shorter it is, the higher the note. 

 Blow across the mouths of two bottles, or tubes closed at one 

 end, one after the other, and you will note that the long bottle, 

 or tube, gives out the lower note. This principle is well illus- 

 trated by Pan's pipes, the flute, or the whistle with movable 

 bottom, directions for making all of which are given in the 

 Field and Laboratory Guide in Physical Nature-Study. When 

 the fife-player holds his finger tips over all the holes, the length 

 of the column of air coincides with the length of the instrument; 

 but when he takes his finger off one hole, the vibrating column 

 ends at this point, reaching in the other direction to the closed 

 end of the instrument (Fig. 171). It is true also that, of two 



