INDEX
Reading edition
A
Abbé, roof prism, 162
Aberration, compensated by minute change of focus, 266
illuminates the diffraction minima, 265
relation determines of focus and aperture, 266
Achromatic long relief ocular, 146
objective, 77
Achromatism, condition for, 78
determination of, 78
imperfection of, 87
Adjustment where Polaris invisible, 235
Air waves, length of, 255
Alt-azimuth mount for reflector, 102
mounts, with slow motions, 102
setting up an, 228
Anastigmats, 84
Annealing, pattern of strain, 68
Astigmatism, 84, 209
of figure, 210
Astronomy, dawn of popular, 19
B
Bacon, Roger, alleged description of telescopes, 6
Barlow lens, 152
“Bent,” objective, 86
Binocular, 2
advantage of, exaggerated, 151
for strictly astronomical use, 152
telescopes for astronomical use, 163
C
Camouflage, in optical patents, 97
Cassegrain, design for reflecting telescope, 22
Cassegrain, sculptor and founder of statues, 22
Cell, taking off from a telescope, 202
Chromatic aberration, 11, 76
investigation of, 210
correction, differences in, 91
error of the eye, 90
Clairault’s condition, 81
two cemented forms for, 81
Clarks, portable equatorial mounting, 109
terrestrial prismatic eyepiece, 158
Clock, the cosmic, 233
Clock drive, 110, 174
Clock mechanism, regulating rate of motor, 179
Coddington lens, 137
Cœlostat constructions, 126
tower telescopes, 127
Color correction, commonly used, 211
examined by spectroscope, 211
of the great makers, 90
Coma-free, condition combined with Clairault’s, 83
Comet seeker, Caroline Herschel’s 118
seekers with triple objective, 119
Crowns distinguished from flints, 64
Curves, struggle for non-spherical, 18
D
Davon micro-telescope, 148
Dawes’ Limit, 261
in physiological factors, 263
Declination circle, 108
adjustment of, 239
Declination circle, adjustment by, 237
facilitates setting up instrument, 110
Definition condition for excellence of, 254
good in situations widely different, 254
DeRheita, 12
constructed binoculars, 13
terrestrial ocular, 13
Descartes’ dioptrics, publication of, 11
lens with elliptical curvature, 12
Dew cap, 219
Diaphragms, importance of, 43
Diffraction figure for bright line, 269
pattern, 256
solid, apparent diameter of, 262
solid of planet, 269
solid for a star, 260
spectra, 190
system, scale of, 260
varies inversely with aperture, 260
through objective, 258
Digges, account suggests camera obscura, 7
Dimensions, customary, telescope of, 24
Discs, inspection of glass, 66
roughing to form, 69
Distortion, 86
Dolland, John, 28
published his discovery of achromatism, 29
Peter, early triple objective, 29
Dome wholly of galvanized iron, 250
Domes, 246
Driving clock, a simple, 174
pendulum controlled, 177
clocks spring operated, 175
E
English equatorial, 110
mounts, mechanical stability of, 113
Equatorial, adjustments of, 230
Equatorial, coudé, 124
mount, different situations in using, 229
mount, first by Short, 104
mount, pier overhung, 115
mount in section, 107
two motions necessary in, 106
Equilibrating levers, devised by T. Grubb, 39
Evershed, direct vision solar spectroscope, 189
Eye lens, simple, preferred by Sir W. Herschel, 136
Eyepiece, compensating, 142
Huygenian, 139
Huygenian, achromatism of, 140
Huygenian, with cross wires, 140
Huygenian, field of, 141
Huygenian focal length of, 143
measuring focus of, 136
microscope form, 147, 148
monocentric, 139
a simple microscope, 134
Tolles solid, 141
F
Field, curvature of, 85
glass, arrangement of parts, 151
Galilean, 150
lens diameter possible, 150
Field lens, 139
Figuring locally, 73
process of, 73
Filar micrometer, 172
Finder, 108, 132
adjustment of, 230
Fine grinding, 69
Fixed eyepiece mounts, 118
Flints, highly refractive due to Guinand, 36
Foucault, 39
development of silver on glass reflector, 41
knife edge test, 212
Foucault, methods of working and testing, 41
Fraunhofer, 36
applied condition of absence of coma, 82
form of objectives, 37
long list of notable achievements, 38
“Front view” telescope, 32
mechanical difficulty of, 33
Furnaces, glass, classes of, 59
G
Galilean telescope, small field of, 9
Galileo, exhibited telescope to senators of Venice, 8
grasps the general principles, 7
produces instrument magnifying 32 times, 8
Gascoigne, William, first using genuine micrometer, 12
Gauss, Objective, 82
Gerrish, application of drive, 181
motor drive, 179
Ghosts, 137
Glass, dark, as sunshade, 166
forming and annealing, 62
inspection of raw, 61
losses by volatilization, 58
materials of, 59
origin of, 57
persistent bubbles in, 58
a solid solution, 57
Grating spectroscopes, 190
Gratings, spectroscope, 189
Gregory, James, described construction which bears his name, 19
failed of material success, 20
Grubb, Sir Howard, objectives, 74
Guinand, Pierre Louis, improvements in optical glass, 36
H
Hadley, disclosed test for true figure, 27
John, real inventor of reflector, 25
Hadley’s reflector, tested with satisfactory results, 26
Hall, Chester Moor, designed first achromatic telescope, 27
had telescopes made as early as 1733, 27
Hand telescope, magnifying power, 150
monocular, 151
Hartmann test, 213
on large objectives, 267
principle of, 214
Hartness, turret telescope, 130, 131
Heliometer, principle of, 171
Hensoldt, prism form, 163
Herschel’s discovery of Uranus, 32
forty foot telescope, 34
Sir John, 35
Sir John, proposed defining condition, 81
Sir William, 31
Herschel’s time, instruments of, 35
Hevelius, construction for objective of 150 feet, 17
directions for designing Galilean and Keplerian telescopes, 14
invention of first periscope, 15
Johannes, 13
mention of advantage of plano convex lens, 14
mentions telescope due to DeRheita, 14
Housing reflector of 36 inch aperture, 243
rolling on track, 242
simplest instrument for fixed, 241
Huygens, Christian, devised methods of grinding & polishing, 16
Huygens’ eyepiece, introduction of, 24
Huygens, sketch of Mars, 16
I
Image, correct extra focal, 208
critical examination of, 204
Image, curvature of, 87
seen without eyepiece, 134
showing unsymmetrical coloring, 208
Interference rings, eccentric, 205
Irradiation, 262
J
Jansen, Zacharius, 4
K
Kellner, ocular, 145
Kepler, astronomical telescope, 10
differences of from Galilean form, 10
Knife edge test of parabolic mirror, 212
L
Lacquer, endurance of coating, 223
Latitude scale, 232
Lenses, determinate forms for, 80
Lens, magnifying power of, 134
“crossed,” 24
polishing the fine ground, 70
power of, 78
triple cemented, a useful ocular, 138
simple achromatic, 137
single, has small field, 137
spotted, cleaning of, 217
Light grasp and resolving power, 265
small telescope fails in, 264
Light ratio of star magnitudes, 264
Light transmitted by glass, 53
Lippershey, Jan, 2
discovery, when made, 5
retainer to, 3
Lunette à Napoleon Troisiéme, 154, 155, 162
M
Magnifying power, directly as ratio of increase in tangent, 135
powers, increase of, 273
Marius, Simon, 5
used with glasses from spectacles, 5
Marius, picked up satellites of Jupiter, 5
Meridian photometer, 194
Metius, James, 4
Metius, tale of, 4
Micrometer, double image, 171
square bar, 171
Micrometers, 168
Micrometry, foundations of, 12
Mirror’s, aberrations of, 92
adjustment of, 206
concave spherical, 92
final burnishing of, 226
hyperboloidal, 96
lacquer coating for surface, 221
mounting, by Browning, 49
parabolic oblique, shows aberration, 95
surface, prevention of injury to, 220
Mittenzwey ocular, 141
Mountain stations, good or very bad, 254
Mounts, alt-azimuth and equatorial, 98
Myopia, glasses for, came slowly, 2
N
Navicula Lyra, stages of resolution of, 271
Newton, abandoned parabolic mirror, 21
blunder in experiment, 20
gave little information about material for mirrors, 23
Isaac, attempt at a reflector, 20
Normal spectra, 190
O
Objective, adjustable mount for, 44
adjusting screws of, 44
Clark’s form, 83
cleansing, 203
examination of, 202
Objective, four-part, 85
Fraunhofer flint-ahead, 83
how to clean, 216
spacers, to take out, 217
typical striæ in, 203
Objective prism, photographing with, 185, 187
Objectives, crown glass equiconvex, 80
over-achromatized, 90
rated on focal length for green 24
Observatories, cost of Romsey, 252
Observatory at small expense, 249
Romsey, description of, 249
with simple sliding roof, 245
Observing box, 229
Oblique fork alt-azimuth, 100
Ocular, apparent angular field of, 146
terrestrial, 147
Tolles terrestrial, 147
typical form, 45
Oculars, radius of curvature of image in, 146
undesirability of short focus, 275
Open fork mount, 115
well suited to big reflectors, 117
Optical axis, to adjust declination of, 238
Optical glass, classes of, 63
data and analysis of, 64
industry, due to single man, 36
production of, 60
Orthoscopic ocular, 145
P
Parallactic mount, 104
Petition for annulment of Dolland’s patent, 29
Photometer, artificial star Zöllner, 194
extinction, 198
photoelectric cell, 199
precision of astronomical, 199
selenium cell, 199
Zöllner, 197
Photometers, three classes in stellar, 193
“Photo-visual, objective,” 89
Pillar-and-claw stand, 98
Pillar mount, 240
Pitch, optician’s, 71
Placement for tripod legs, 236
Polar and coudé forms of reflector, 125
axis, adjustment of by level, 232
axis, alignment to meridian, 232
axis, setting with finder altitude of, 234
telescope, 119, 122
Polaris, hour angle of, 233
a variable star, 199
Polarizing photometer, 193
Pole, position, 234
Polishing machine, 70
surface of tool, 72
tool, 71
Porro’s second form, 157
work, original description of, 156
Porta, description unintelligible, 7
Portable equatorial, adjustment of, 230
telescopes, mounting of, 228
Porter polar reflector, 130
Position angle micrometer of Lowell Observatory, 173
Powers, lowest practicable, 276
Prismatic inversion, Porro’s first form, 155
Prismatic inverting system, the first, 154
Prisms, Dove’s, 154
Prism field glasses, stereoscopic effect of, 159
Prism glass, 152
loss of light in, 160
objectives of, 161
weak points of, 160
R
Resolving constant, magnification to develop, 275
power and verity of detail, 2
power of the eye, 274
Reticulated micrometer, 169
Reversion prism, 153
Right ascension circle, 108
Ring micrometer, 169
computation of results of, 170
Ring system faults due to strain, 205
“Romsey” observatory type, 248
Rack motion in altitude, 100
Ramsden, ocular, 144
Reflection, coefficient of, from silvered surface, 54
Reflector costs, 55
cover for, 242
development in England, 41
for astrophysical work, 56
light-grasp of, 53
relative aperture of, 50
section of Newtonian, 45
skeleton construction, 49
suffers from scattered light, 56
working field of, 55
Refractive index, 63
Refractors and reflectors, relative advantages of, 52
few made after advent of reflector, 27
in section, 43
light transmission of, 53
Refractors, relative equivalent apertures of, 54
tubes of, 42
S
Scheiner, Christopher, use of Kepler’s telescope, 11
devised parallactic mount, 11
Secondary spectrum, 87
new glasses reducing, 88
Seeing, 257
conditions, for difference of aperture, 257
conditions generally bad, 253
standard scale of, 256
true inwardness of bad, 253
Separating power, to compute, 261
Short, James, mastered art of figuring paraboloid, 27
took up Gregorian construction with success, 27
Shortened telescope, 152
Sights, on portable mount, 229
Silver films, condition of, 54
Silvering, Ludin’s process, 225
processes, 222
process, Dr. Brashear’s, 222
Sine condition, Abbé’s, 82
Slit, spectroscope, Abbé type, 184
Snow cœlostat telescope, 127
Solar diagonal, 166
eye piece diaphragms in, 168
early spectroscopes, 188
polarizing eyepiece, 167
spectroscope, 187
Spacers, 44, 218
Spectacle lenses, combination of, 2
Spectacles for presbyopia, 2
invention of, 1
Spectra, visibility of stellar, 183
Spectro-heliograph, principle of, 191
simple type of Hale’s, 191
Spectroscope, 182
construction of astronomical, 182
of Lowell refractor, 185
ocular, McClean form, 183
Specula, small, methods of support, 49
Speculum metal composition of, 24
Sphenoid prisms, 158, 163
Spherical aberration, 11
amount of, 80
annulling in both directions, 84
examination for, 207
quick test of, 267
remedy for, 79
concave mirror, errors of, 22
Star, appearance of, 204
artificial, 66, 203
diagonal, 165
disc, apparent diameter of, 259
image of reflector, 206
Steinheil, achromatic ocular, 144
Karl August, silvering specula, 39
Striæ, location of, 67
Surface, treatment of deterioration of, 218
T
Taylor, triplets with reduced secondary spectrum, 89
Telescopes, choice and purchase of, 201
Early in 1610 made in England, 6
first, 3
the first astronomical, 9
improvement of early, 11
lineage of, 1
name devised, 9
Telescopes, portable and fixed, 108
1609, for sale in Paris, 5
size and mounting of early, 14
Telescopic vision, discovery of, 2
Templets, designed curves of, 69
Tests for striæ and annealing, 68
Transparency, lack of in atmosphere, 255
Triplet, cemented, 85
Turret housing of reflector, 244
V
Variable stars, 192
W
Wedge calibrated by observation, 197
photographic, 197
photometer, 197
Wind, shelter from, 240
Z
Zeiss, binocular of extreme stereoscopic effect, 161
Zöllner, photometer modification of, 198
Zonal aberration, 209