Ellis's tuning fork tonometer; nine cases containing 105 tuning forks giving pitch from 216 to 586.12 vibrations per second, with six holders for forks; hammers & pad to set forks vibrating. Ellis's tuning fork Tonometer 1880
Two prototype tonometers for teaching speech intonation to the deaf, c. 1955 Two prototype tonometers for teaching speech intonation to the deaf
