An introduction to astronomy: designed as a text-book for the use of students in college. By Denison Olmsted ...

ANALYSIS. Xlll
Art. Art.
Why those of Mercury in May and Satellites-number-peculiarities.... 350
November..... 315 NEPTUNE -distance - diameter
Why those of Venus in June and De- period............................ 51
cember............... 315 History of its discovery.......... 351-353
Intervals between the transits of Mer- Agreement of observation with theory 353
cury 316 Simultaneous discovery............. 353
Intervals between the transits of Results obtained by Walker......... 353
Venus........................... 316 PLANETARY MOTIONS —two methods
How found................. 316 of studying them................. 354
Why so great an interest is attached Appearances viewed from the sun... 355
to the transits of Venus........... 317 Motions of Mercury explained....... 355
Why tile sun's horizontal parallax Form of orbit not seen from the sun. 355
cannot be found like the moon's.. 317 Why diagrams and orreries represent
Why distant places of observation them erroneously................. 57
are taken,, 318 App.arent motionsa of the planets.. 858
Process for the sun's hor. par. ex- Two causes make them unlike the
plained from Fig. 63.............. 318 real...... 358
Stun's bor. par. in seconds.......... 318 Apparent motions illustrated by
To find the hor. par. of Venus and of Fig. 69........................ 359
Mars............. 318 Apparent motions of the Superior
Atmosphere of Venus............... 319 Planets 860
Satellites of Mercury and of Venus? 319 Illustrated by Fig. 70. 361
Chapter X.-SUPERIOR PLANETS-ASTER- Chapter Xl. —DETERMINATION OF TIHE
OIDs-Mo TIONS OF THE PLANETS. PLANETARY ORBITS-KEPLER'S DIscov]RIES-ELEMENTS OF THE ORBITS OF THE
Superior Planets, how distinguished PLANELMES OF HE ORBIS OF HE
from the Inferior.P.............. 320
MARS-size —distance from the sun.. 321 Figure of the planetary orbits-anChanges in apparent magnitude and cient ideas........... 362
brightness...................... 321 Notions of Ptolemy and Hipparchus. 362
Phases of Mars, Fig. 64....... 22 Kepler-Investigation of the motions
Telescopic appearances.............. 323 of Mars.......................... 363
Satellite 2-ellipticity............... 323 Discovery of the first law-the second
To find the hor. par. of Mars........ 324 -the third 3.............,..363-365
ASTEROIDS-history of the first four. 325 Modification of the third law........ 366
Distance fiom the sun-size-orbits. 326 ELEMENTS OF THE PLANETARY ORBITS
Modes of naming.................3.. 867
JUPITER-magnitude-figue-figure-diurna Why not found like the lunar and
revolution........................ 328 solar orbits....................... 368
Inclination of the axis to the orbit, First steps of the process for finding
and change of seasons............. 328 the elements..................... 369
Telescopic appearances............. 329 To convert geocentric longitudes and
Belts described and explained....... 380 latitudes into heliocentric, Fig. 71.. 369
Satellites-how seen-names........ 331 To determine the position of the
Maglnitude-distances-periods...... 332 nodes................... 371
Orbits-form-inclination........... 333 To determine the inclination........ 371
Eclipses-their various, phenomena, To find the periodic time............ 872
Fig. 65...................... 334-335 The position of a planet which is
Shadows cast by the satellites on the most favorable for finding the elePrimary..................... 336 ments............................ 373
Longitude from the eclipses of Ju- Exemplified in finding the periodic
piter's satellites...............338-339 time of Saturn................... 874
Velocity of light, how discovered... 340 To determine the distance from the.
SATuRN-si ze-ringg-telescopic view..341 sun.................... 375
Ring described............ 342 How the mean distance is found..... 375
Dimensions of the system............ 342 How the distance at any point in the
Thinness, of the rings. 342 orbit............... 75
Revolution of the rino around the Method for the Inferior Planets...... 375
sun...........................343-344 Method for the Superior, Fig. 73..... 375
Its chan es and disappearances ex- To determine the place of the periheplained........................345-346 lion.............................. 376
Revolution of the ring in its own To determine the epoch of passing the
plane............................ 347 perihelion................... 3.... 76
Satellites of Saturn-number and To find the eccentricity.............. 377
inamtues...................... 848 QUANTITY OF MATTER IN THE SUN AND
Eclipses........................... 48 PLANETS................ 378
URANUs-its discovery.............. 349 How found in terms of the distances
Size-periodic time-inclination..... 349 and periodic times................ 79