e, 270;
on Mars, 277

Tennant, eclipse observations, 168, 169, 174

Terby, surface of Mars, 278, 279, 281;
secondary tail of comet, 355

Thalen, basic lines, 207;
map of solar spectrum, 210;
solar elements, 212

Thollon, line-displacements by motion, 202, 364;
atlas of solar spectrum, 211, 440;
lunar atmospheric absorption, 264

Thome, comet discovered by, 361

Thomson, Sir William (Lord Kelvin), solar chemistry, 138;
magnetic influence of the sun, 161;
tidal strains, 257;
rotation of the earth, 273;
dynamical theory of solar heat, 311, 312

Thraen, period of Wells's comet, 357

Tidal friction, effects on moon's rotation, 271, 272, 318;
month lengthened by, 316, 318;
influence on planets, 319-322;
on development of binary systems, 420

Tietjen, asteroidal orbits, 284

Tisserand, capture of comets, 98;
lunar acceleration, 273;
revolutions of Neptune's satellite, 305;
stationary radiants, 341;
perturbations of Algol, 391;
director of Paris Observatory, 414

Titius, law of planetary intervals, 71, 72, 85

Todd, eclipse of 1887, 185;
solar distance, 236, 241;
trans-Neptunian planet, 306

Tornaghi, halo round Venus, 254

Transit instrument, 120

Trepied, reversal of Fraunhofer spectrum, 172

Troughton, method of graduation, 122

Trouvelot, veiled spots, 148;
chromosphere in 1878, 175;
intra-Mercurian planets, 181, 250;
observations of prominences, 184, 196, 204;
of Mercury, 245, 247;
rotation of Venus, 252;
red spot on Jupiter, 296

Trowbridge and Hutchins, carbon in sun, 212

Tschermak, origin of meteorites, 339

Tupman, transit expedition, 235;
results, 236

Turner, polariscopic coronal photography, 189;
employment of coelostat, 190, 438;
stationary radiants, 341

Ulloa, eclipse of 1778, 69

United States, observatories founded in, 6, 7

Uranus, discovery, 5, 74, 111;
unexplained disturbances, 78, 79, 307;
satellites, 87, 303;
equatoreal markings, 303, 304;
spectrum, 304, 305;
retrograde rotation, 313, 315, 322

Valerius, darkening of sun's limb, 221

Vassenius, description of prominences, 68

Venus, transits, 4, 229, 232;
of 1874, 233-236;
of 1882, 239, 240;
atmosphere, 236, 253, 254;
mountains, 252, 253;
spectrum, 254;
albedo, 255;
ashen light, 2