Paget believed that speech originated in the "pantomimic action" of the lips and tongue related to the speaker's senses and emotions. This led to his central thesis that hand signs and gestures were the original form of human communication, and that humans had evolved to communicate vocally as their "hands [were] full".  He reviewed the history of devices for speech synthesis, and described his experiments on the nature of vowel and consonant sounds artificially produced by models. The latter part of the book concerned with voice production, the treatment of speech defects, how to teach deaf mutes, the principles of ventriloquism, and how to improve language and spelling. Digital facsimile from the Internet Archive at this link.