Telescope, reflecting, 209, 255
varieties of, 254, 257

Newton's, 258

Herschel's, 255, 260

Thales, 20

Thomson, quoted, 3, 29, 36, 49,
66, 70, 79, 102, 151, 152, 221

Tides, 162

Spring and Neap, 167
Aërial, 174

Time, 267, 278
Tomlinson, C., quoted, 196
Transits, 75
Trigonometry, 243
Tripe de Roche, 67
Tropics, 141
Twilight, 157

Tycho Brahé, 24, 208, 286

Umbra, 124

Uranus, 206, 254, 257

angle subtended by, 208
density of, 208

dimensions, motions, and
distance from the Sun, 207
satellites of, 209, 257

69, 101

apparent annual motion

of, 269, 270, 275

apparent diameter of, 86

atmosphere of, 91

brilliancy of, 80, 83