and on Reed Organ-Pipes. 239 



reed a cylindrical tube of any length from nothing to AB, then 

 if the tube be pushed back, and a joint EF equal to AB be 

 fitted on, a fresh drawing out of the tube will shew the effect 

 of any length from AB to double AB, and in this way with 

 different joints we may go on to any length we please. The 

 results of experiments with this apparatus, I will describe in 

 general terms, 



No. 1. 



lEA O U U O AEl TEA O U 



a h c d 



Let the line abed represent the length PB of the pipe measured 

 from a, and take ah, be, cd, &c., respectively equal to the length 

 of the stopped pipe in unison with the reed employed, that is, 

 equal to half the length of the sonorous wave of the reed. 



The lines in these diagrams must, in fact, be considered as 

 measuring rods placed by the side of the tube ABCD with their 

 extremity a opposite to the piston P, the letters and other 

 indications upon them shewing the effect produced when the 

 extremity B of the pipe reaches the points so marked, and the 

 distance therefore from these points to a respectively being the 

 length of the pipe producing the effects in question. 



Now if the pipe be drawn out gradually, the tone of the 

 reed, retaining its pitch, first puts on in succession the vowel 

 qualities I E A O U; on approaching c the same series makes 

 its appearance in inverse order, as represented in the diagram. 



* la speaking of musical notes, I shall denote their place in the scale by the German 

 tablalure, the octave from tenor c to 6 on the third line -of the treble is marked once 

 thus c', the next above, twice, c" and so on. As a standard for the pitch, 1 use a pitch- 

 pipe which is made to sound by a small pair of attached bellows yielding a constant 

 pressure of 2 . 5 in. The internal dimensions are .85 by .9 in., and 1 foot long. Lumiere .16 in. 

 An attached scale is graduated to shew the actual length of the pipe (that is, the distance 

 from the bottom of the pipe to the bottom of the piston) in English inches and decimals. 



