branous bags ; situated on each side, above the Hpsr 

 of the glottis. What is remarkable is, that each lid 

 is cloven almost its whole length. By this cleft each 

 lip has a communication with the bag belonging to it. 

 And the motions of these bags produce most of the 

 sounds peculiar to this animal. 



Though the voice of birds bears a nearer resemblance 

 to ours, than that of a quadruped's, yet their organs 

 have far less resemblance to ours, and contain a greater 

 number of singularities. They, like us, have a glottis 

 at the top of the trachea ; but they have another at 

 the bottom of it, which much contributes both to the 

 strengthening and modifying of (heir voice. These have 

 different membranes, more or less fine, more or less 

 bent, and in a variety of positions. In some birds, 

 as in geese, there are four of these, figured and disposed 

 like the reeds in hautboys. 



With regard to the human vtfice, an ingenious man 

 observes, " sitting in. company, I chanced to take 

 notice, that in ordinary discourse, all that is spoke, is 

 spoken in perfect notes ; and that some of the com- 

 pany used eighths, some fifths,and others thirds. 1 ob. 

 served likewise of him whose speech, vras the most 

 pleasing, that all the tones he used, consisted either 

 of concords, or of such discords as made up harmony." 

 Cutting the trachea was long reputed mortal ; but 

 \t is now usual to opeji it in dangerous quinsies. This 

 physicians were at .tirst encouraged to do, from the 

 case of a Cornish gentleman, who had hLs wind. pipe 

 quite cut through, and yet was cured and lived several 

 years after. 



38. In order to the admission and expulsion of the 

 air by the lungs, it is necessary the breast should be 

 contracted and dilated. This end is served by the 

 bony part of the Thorax, the intercostal muscles, and 

 the diaphragm, a broad, muscular part, reaching across 

 the breast, and dividing the middle from the lower ca- 

 vity. It runs obliquely from the sternou and ribs be- 

 fore to the vertebrae of theloins behind. 



