Trade and trades, 12, 51, 68 _et seq._, 107, 115, 118. Transformation Theory, 249 _et seq._ Trigonometry, 46, 49, 55. Turgot, 121. Tycho Brahe, 87 _et seq._ Tyndall, 260-61. Uranus, 184 _et seq._ Vacuum, 95. Varro, 38. Vesalius, 78. Vitruvius, 30 _et seq._ Viviani, 94. Vivisection, 38, 71, 80. Volcanoes, 40, 136. Volta, 177. Vulcanist, 131, 137. Wadham College, 104. Walker, 195. Wallace, 211, 231. Wallis, 103. War, 46, 178, 213 _et seq._ War-engines, 28, 34. Watch, 94. Water, 157, 177. Water-clocks, 13, 94. Watt, Gregory, 172. Watt, James, 133, 156, 157. Wedgwoods, 138, 173, 199. Weighing, 7, 10, 86. Werner, 129 _et seq._ Wilkins, 101, 104. Willis, 104. Willughby, 109, 110. Wine, 220, 226. Wollaston, 119. Wool, 226. Wren, 104, 107. Wright, 143 _et seq._ Wundt, 258, 259. Xenophon, 117. Young, 258, 279. Zacharias, 92. Zodiac, 9, 33. Zoölogy, 7, 12, 21, 24, 25, 37, 53, 66, 109, 110, 197 _et seq._ * * * * * * Transcriber's note: The following is a list of changes made to the original. The first line is the original line, the second the corrected one. parabola, hyperbola--play a large part in the subsequent parabola, the hyperbola--play a large part in the subsequent Seneca, _Physcial Science_; translated by John Clarke. Seneca, _Physical Science_; translated by John Clarke. College by 1558 it was the custom to remain for discussion College by 1658 it was the custom to remain for discussion slowly with the result that it had a stony, rather a slowly with the result that it had a stony, rather than a This would correspond to 325° January 1, 1847. This would correspond to 325° on January 1, 1847. sometimes, in the case of the γ rays with velocity sometimes, in the case of the γ rays, with velocity positively and negatively chasged particles. Rutherford positively and negatively charged particles. Rutherford