affected by barometric pressure, 117
astronomical, 115
astronomical, how mounted, 116
astronomical, its dial, 116
error of, determined with transit, 118
jeweller's regulator, 114
of telescope, 175
Clusters of stars, photography of, 98
Columbia University Observatory, latitude observations, 139
polar photography, 196
Common, his reflecting telescope, 32
Confusion of dates, in Pacific Ocean, 125
Congress of Astronomers, Paris, 1887, 102
Constellations, 162
Control, "mouse," for photography, 88
Copernican theory of universe, 53, 56
demonstration, 94
Corkscrew tunnels, 220
Crape ring of Saturn, 144
Cumulative effect, in photography, 84
Date, confusion of, in Pacific Ocean, 125
Date-line, international, explained, 126
Development of photograph, 81
Dial, of astronomical clock, 116
"Dialogue" of Galileo, 53
Differences of time, explained, 121
Directions, telescopic measurement of, 21
Directory of the heavens, 103
Distance, of light-source in photography, 83
of stars, 94, 106, 158
of Sun, 67, 97, 106
Donner, polar photography, 195
Double telescopes, for photography, 86
Earth, motions of its pole, 131
rotation of, 136, 162, 171, 184
shape of, 135
Eclipses, photography of, 109
Elkin, measures Pleiades, 15
Equatorial telescope, explained, 170
Eros, discovered by Witt, 66, 105
its importance, 67
Error of clock, determined by transit, 118
Exposure, length of, in photography, 84
Feldhausen, Herschel's observatory near Capetown, 204
Fiji Islands, their date, 126
Fixed polar telescope, 197
"Following" the stars, 88, 173
Four-day cycle of pole-star, 24
France, outside time-zone system, 129
Fundamental longitude meridian, 124
GALILEO, 47
and the Church, 48
discoveries of, 49
observes Saturn, 141
Galle, discovers Neptune, 61
Gauss, computes first asteroid orbit, 60
Gautier, Paris, constructs big telescope, 179
Geodetic Association, international, 139
Geography, maps, astronomical side of, 112
Geology, polar motion in, 131
Gill, photographs comet, 100
Gilliss, at Naval Observatory, Washington, 169
Goldsborough, at Naval Observatory, Washington, 169
_Grande Lunette_, Paris, 1900, 176, 180
Gravitation, 13
in Pleiades, 14, 212
law of, Newton's, 212
Gravity, centre of, 217
Greenwich, origin of longitudes, 7, 124
time, 7
Groombridge, English astronomer, 1
Harrison, inventor of chronometer, 8
Head, of heliometer, 156
Heidelberg, photography at, 104
HELIOMETER, 152
head of, 156
how used, 157
principle of, 154
scales of, 158
semi-lenses of, 155
Helsingfors observatory, polar photography at, 195
Henry, measures Pleiades, 11, 17
Hercules, constellation, solar motion toward, 222
Herschel, discovers apex of solar motion, 221
discovers Uranus, 59, 141
John, the moon hoax, 200
Hipparchus, discovers precession, 186
early star-catalogue, 21, 39
invents star magnitudes, 91
Huygens, announces rings of Saturn, 142
his logogriph, 143
Ice-cap, of Earth, 131
_Index Librorum Prohibitorum_, 53
International, date-line, explained, 126
geodetic association, 139
Inter-stellar motion, in clusters, 98
in Pleiades, 14
Islands of Pacific, their longitude and time, 125
Japan, latitude station in, 139
Jewellers' correct time, 121
Journalistic astronomy, 176
Jupiter's satellites, discovered by Galileo, 50
discovered by Barnard, 51
Keeler, observes Saturn's rings, 140, 147, 150
photographs nebulæ, 32
"Keyhole" nebula, 205
Lambert, determines longitude of Washington, 168
Laplace, discusses Saturn's rings, 146
nebular hypothesis, 33
stability of solar system, 210
Latitude, changes of, 133, 138
definition of, 134
determining the, 6
Leverrier, predicts discovery of Neptune, 61, 142
Lick Observatory, Keeler's observations, 140
Light, undulatory theory of, 19, 148
Light-waves, measuring length of, 20, 149
Logogriph, by Huygens, 143
Long-exposure photography, 85
Longitude, counted East and West, 125
determining, 6
determining by occultations, 167
effect on time differences, 123
explained, 123
of Washington, first determined, 168
Maclear, observes Eta Argus, 205
Magnitudes, stellar, 91
Manila, its time, 127
Maps, astronomical side of, 112
Meridian circle, explained, 189
Milky-way, poor in nebulæ, 33
Minor Planets, see Asteroids.
MOON, HOAX, 199
motion among stars, 163
mountains discovered by Galileo, 49
size of, measured, 166
Motion of moon, 163
MOTIONS of the EARTH'S Pole, 131
MOUNTING GREAT TELESCOPES, 170
Naked-eye nebulæ, 28
Naples, Royal Observatory, latitude observations, 139
Naval Observatory, Washington, noon signal, 120
NAVIGATION, 1
before chronometers, 3
use of astronomy in, 113
NEBULÆ, 27
Nebula, in Andromeda, 28
in Orion, 30
"keyhole", 205
Nebular, hypothesis, 33
structure in Pleiades, 17
Nebulous stars, 31
Negative, and positive, in photography, 82
Neptune, discovery predicted by Leverrier, 61, 142
discovery by Galle, 61
Newcomb, fixes apex of solar motion, 222
Newton, law of gravitation, 212
longitude commission, 8
New York, its telegraphic time system, 120
Noon Signal, Washington, 120
Number, of nebulæ, 31, 33
of temporary stars, 38
Nutation, explained, 188
Occultations, 161
explained, 165
Occultations, use of, 166, 167
Orion nebula, 30
Pacific islands, their longitude and time, 125
Parallax, solar, 67, 106
stellar, 94, 106
measured with heliometer, 158
Paris, congress of astronomers, 1887, 102
exposition of 1900, 176
Periodic motion of earth's pole, 133
Perseus, constellation, temporary star in, 46
Philippine Islands, their time, 127
Photography, asteroid, invented by Wolf, 104
congress of astronomical, 102
cumulative effect of light, 84
distance of light-source, 83
double telescopes for, 86
general star-catalogue, 102
IN ASTRONOMY, 81
in discovery of asteroids, 64, 104
in solar physics, 109
in spectroscopy, 108
length of exposure, 84
measuring-machine, Rutherfurd, 93
motion of telescope for, 87
"mouse" control of telescope, 88
of eclipses, 109
of inter-stellar motion, 99
Paris congress, 1877, 102
polar, 191
Rutherfurd pioneer in, 90
star-clusters, 98
star-distances measured by, 94
summarized, 110
wholesale methods in, 103
Piazzi, discovers first asteroid, 59, 106
Pitkin, report to House of Representatives, 168
Planetary nebulæ, 31
PLANET OF 1898, 58
Planetoids, see Asteroids.
Planets known to ancients, 58
PLEIADES, 10
gravitation among, 212
motion among, 14, 16, 98
nebular structure, 17
number visible, 11
Polar axis, of telescope, 173
Polar photography, 191
at Helsingfors, 195
Pole, celestial, 184
of the earth, motions of, 131
THE ASTRONOMER'S, 184
POLE-STAR, 18
as a binary, 25
as a triple, 18, 26
change of, 187
its four-day cycle, 24
motion toward us, 24
Positive, and negative, in photography, 82
Potsdam, observatory, photographic star-catalogue, 103
Practical uses of astronomy, 112
Precession, explained, 186
Prize, for invention of chronometer, 8
Ptolemaic theory of universe, 56
Ptolemy, writes concerning Hipparchus, 39
Railroad time, explained, 127
Refraction, atmospheric, explained, 193
"Regulator," the jeweller's clock, 114
Ring-nebulæ, 31
Rings, of Saturn, see Saturn's rings.
Roberts, Andromeda nebula, 28
Rotation, of Earth, 136, 162, 171, 184
of Saturn, 150
Royal Astronomer, his duties, 2
Royal Observatory, Greenwich, 124
Greenwich, Bradley's observations, 219
Naples, latitude observations, 139
Rutherfurd, cluster photography, 99
invents photographic apparatus, 93
pioneer in photography, 90
stellar parallax, 94
Sagredus, character in Galileo's Dialogue, 55
Salusbury, Galileo's translator, 50, 54
Salviati, character in Galileo's Dialogue, 55
Samoa, its date, 126
SATURN'S RINGS, 140
analogy to planetoids, 147
announced by Huygens, 142
observed with spectroscope, 147
shown to be double by Cassini, 144
structure and stability, 145
Scales, of heliometer, 158
Scorpio, constellation, temporary star in, 39
Semi-lenses of heliometer, 155
Sextant, how used, 4
Sicily, latitude station in, 139
_Sidereus Nuncius_, published by Galileo, 52
Simplicio, character in Galileo's Dialogue, 55
Sirius, brightest star, 205
Size of Moon, measured, 166
_Société de l'Optique_, 177
Solar parallax, see Sun's distance.
physics, by photography, 109
system, stability of, 210
Spectroscope, its use explained, 147
used on pole-star, 19
to observe Saturn's rings, 147
Spiral nebulæ, 31
Stability, of Saturn's rings, 145
of Solar System, 210
Standards, time, of the world, 111
table of, 130
"Standard" time, explained, 127
Star-catalogue, general photographic, 102
Star-clusters, photography of, 98
Star-distances 94, 106
measured with heliometer, 158
Rutherfurd, 94
Star magnitudes, 91
Star-motion, toward us, 21
Star-tables, astronomical, 118
Stars, variable, 42
St Gothard railway, tunnels, 220
Sun, newspaper, the moon hoax, 201
SUN-DIAL, HOW TO MAKE A, 69
SUN'S, DESTINATION, 210
distance, compared with star distance, 97
measured with Eros, 67, 106
motion, apex of, 221
Sun-spots, discovered by Galileo, 49
_Systema Saturnium_, Huygens, 143
Telescope, clock, 175
at Paris Exposition, 176, 180
double, for photography, 86
equatorial, explained, 170
first used by Galileo, 49
motion of, 87
mounting great, 170
unmoving, for polar photography, 197
TEMPORARY STARS, 37
in Andromeda nebula, 28, 29, 45
in Aquila, 40
in Cassiopeia, 40
in Perseus, 46
in Scorpio, 39
their number, 38
theory of, 42
Time, correct, determined astronomically, 113
differences between different places, 121
TIME STANDARDS OF THE WORLD, 111
standards of the World, table of, 130
system, in New York, 120
zones, explained, 128
Trails, photographic, 191
Transit, for determining clock error, 118
Tycho Brahe, his temporary star, 40
Ulugh Beg, early star-catalogue, 21
Undulatory theory, of light, 19, 148
Universe, theories of, 34, 53, 56
Uranus, discovered by Herschel, 59, 142
Use of occultations, 166, 167
Uses of astronomy, practical, 112
Variable stars, 42
in Argo, 205
Vega, future pole-star, 187
Visibility of stars, in day-time, 191
Vision, phenomenon of, 20, 149
Washington, its longitude first determined, 168
Waves, explained, 148
of light, 20, 148
Wilkes, at Naval Observatory, Washington, 169
Wilkins, imaginary voyage of, 208
Witt, discovers Eros, 66, 105
Wolf, M, invents asteroid photography, 104
measures Pleiades, 11
World's time standards, table of, 130
Yale College, Pleiades measured at, 15
Zones, time, explained, 128
TRANSCRIBER'S NOTE
Italic text is denoted by _underscores_.
Fractions in the two tables on pg 74 and pg 78 are displayed in the form
"a-b/c" as 4-1/2 or 2-7/16 for example. The original text in the
tables used the form "a b-c". A few other basic fractions in the text
such as ½ and ⅖ are displayed in this same form in the etext.
There is only one Footnote in this book, with its anchor on pg 69.
It has been placed at the end of the chapter containing the anchor.
Obvious typographical errors and punctuation errors have been
corrected after careful comparison with other occurrences within
the text and consultation of external sources.
Except for those changes noted below, all misspellings in the text,
and inconsistent or archaic usage, have been retained. For example,
time zone, time-zone; Le Verrier, Leverrier; light wave, light-wave;
intrust; wabbling; unexcelled; crape; monumented.
Pg 146, 'James Clark-Maxwell' replaced by 'James Clerk Maxwell'.
Pg 189, 'impossible to measure' replaced by 'possible to measure'.
End of Project Gutenberg's Practical Talks by an Astronomer, by Harold Jacoby