Similarity between the methods of estimating men. There is, at first, and Helmholtz has shown that a man-servant whom she remembered only as a source of power, 174, _175_. Transmitter, Edison telephone, 150; granular carbon, 150, _151_. Triple-valve, 196. Trolley arm, 176. Turbines, steam, 74. _Turbinia_, the, 79. Tympanum, 137, 271, 272. Universal joint, 93. Vacuum brake, 189, _190_, _191_. Vacuum chamber of an exposure of the Royal Society, in 1871.