Stammering
2 of the 7 encyclopedias on this shelf carry an entry for Stammering. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
or STUTTERING, an infirmity of speech, the result of fail ure in co-ordinate action of certain muscles and their appropriate nerves. It is analogous to some kinds of lameness, to cramp or spasm, or partial paralysis of the arms, wrists, hands, and nd fingers, occasionally suffered by violinists, pianists, and swordsmen; to the scrivener's palsy, or writer's cramp, of men who write much. Stammering may be hereditary, and it may be acquired by imitation. It may be the result of mental strain or shock. Fever may bring it on, epilepsy, hysteria, and nervous affection, temporary failure of health, any excitement, soreness of the mouth. It rarely shows itself earlier than at 4 or 5 years of age. It usually begins in youth, but may be produced at any later age. Štammering occurs in the mouth, the organ of articulation. Its proximate cause is always in the larynx, the organ of voice. Sometimes the lungs, the organ of breathing, complicate the uncertainty and unsteadiness of the vocal cords and the vocal chink in the larynx. Stammering can be cured. It often cure. Improvement generally takes place as age advances. In some cases resolute endeavor is demanded. A waving motion of the arms, time kept to a baton, were favored as cures at one time. They were on the lines of the musical methods of cure-intoning, chanting, singing-which were based on the fact that most stammerers can sing. These brief instructions should be tried. Regulate the breath. Work for a habitual use of the chest voice-i. e. for deeper, steadier vibration of the vocal chords-because people generally stammer in a head voice. Take exercise, in a chest voice, on the sound (seldom vowels) at which a stumble is apt to be made. Special attention should be paid to possible ssible eye-strain, difficult nasalbreathing, adenoid growths, and diseased tonsils.
Aiton's Encyclopedia (1910)
a defect of speech, due, it is now thought, to a want of exact connection between certain nerves and their appropriate muscles. It was thought formerly that stammering and stuttering, which is really akin to it, were caused by some malformation of the orange of speech; but investigation does not support this theory. Some sounds are harder to utter than others. T and S sounds, if any, are likely to occasion hesitation in speech. A recent writer states that stammerers are common throughout the British Islands and among all English-speaking people, in Germany and in Scandinavia, but are almost unknown in Italy and France. He raises the question whether the greater difficulty of uttering the Anglo-Saxon speech, as compared with the soft speech of southern Europe, may not be one of the causes of stuttering. Speaking in rhythmic movement in time with some musical instrument, as well as diverting the mind by waving the arms, are suggested as helpful to the stuttering speaker.