We now come to the department of the organ which will be of more interest to the listener, viz., the various organ tones. The general shape and construction of the pipes now in use, judging from the earliest drawings obtainable, have not changed for hundreds of years. The ancients were not wanting in ingenuity and we have pictures of many funny-looking pipes which were intended to imitate the growling of a bear (this stop was sometimes labeled Vox Humana!), the crowing of a cock, the call of the cuckoo, the song of the nightingale, and the twitter of the canary, the ends of these pipes being bent over and inserted in water, just as the player blows into a glass of water through a quill in a toy symphony. Then there was the Hummel, a device which caused two of the largest pipes in the organ to sound at once _and awake those who snored during the sermon_! Finally there was the Fuchsschwanz. A stop-knob bearing the inscription, "Noli me tangere" (touch me not), was attached to the console. As a reward for their curiosity, persons who were induced to touch the knob thereby set free the catch of a spring, causing a huge foxtail to fly into their faces--to the great joy and mirth of the bystanders. In order to understand what follows we must make a short excursion into the realm of acoustics. We have already remarked upon the extreme antiquity of the Flute. The tone of the Flute is produced by blowing across a hole pierced in its side; in other words, _like a stream of wind striking upon a cutting edge_. It is possible to produce a tone in this way by blowing across the end of any tube made of any material, of glass, or iron, or rubber, or cane, or even the barrel of an old-fashioned door key. The primitive Flutes found in the Egyptian tombs and also depicted on the ancient hieroglyphics are made of reed or cane, about 14 inches long, possessing the usual six finger-holes. The top end is not stopped with a cork, as in the ordinary Flute, but is thinned off to a feather edge, leaving a sharp circular ring at right angles to the axis of the bore. By blowing across this ring a fair but somewhat feeble Flute tone is produced. The six holes being closed by the fingers, the ground tone of the tube is produced. On lifting the fingers in successive order from the bottom end, we get the seven notes of the major scale. Closing the holes again and blowing harder, we get the scale _an octave higher_. By blowing still harder we get an octave higher still. In other words, we are now producing _harmonics_. It is possible to produce from a plain tube without finger-holes or valves, such as the French Horn, by tightening the lips and increasing the pressure of the player's breath, the following series of harmonics: [Illustration: Series of harmonics]