Category: Essays, Letters & Speeches

Birds and All Nature, Vol. 4, No. 6, December 1898 Illustrated by Color Photography

All animals with lungs have some sort of contrivance in the windpipe that is able to set the air in vibration as it is expelled or inhaled. Some have not only this means of making vocal sound, but have also power to vary the quality and intensity of it. Out of this second abil...