# Spectacles and Eyeglasses/Index

* Adjustment of eyeglasses, 97
** of spectacles, 91
* Airy, discoverer of astigmatism, 23
* Alhazen, 19
* Ancient glass, 17
* Angle, deviating, of a prism, 84, 89
** refracting, 84, 87
* Apex of a prism, finding the, 83
* Assyrians, knowledge of lenses among, 18
* Astigmatism, discovery of, 23
* Asymmetry of the face, 97
* Bar spring eyeglasses, 46
* Bifocal glasses, 42
** invention of, 23
** varieties of, 44
* Brewster, Sir David, 18, 23
* Bridge, width of base of, 73
** relation of top of to plane of glasses, 58, 72
** height of, 71
* Bridges, manufacture of, 38
** varieties of, 40
* Care of spectacles, 100
* Cemented bifocals, 44
* Centering and decentering, 49
** normal lateral, 55
** normal vertical, 56
** of spectacles for constant use, 55
*** near work, 55, 57
* Centrad, 53, 85, 86, 90
* Chemical composition of glass, 29
* Component parts of spectacles, 27
* Conformation of nose pieces, 98
* Crown glass, 29
* Cylinder, finding the axis of, 81
* Date of invention of spectacles, 20
* Decentered lenses, 50
** prismatic effect of, 51
* Deviating angle of a prism, 84, 89
* Dioptric system, 33
* Di Spina, Alessandro, 20
* Discovery of astigmatism, 23
* Distance between the pupils, 51, 67
** between temples, 94
** of the glasses from the eyes, 57
* Emerald used by Nero, 18
* Epicanthus, eyeglasses for, 48
* Eyeglasses, advantages and disadvantages of, 26
** inspection and adjustment of, 76, 97
** prescription of, 75
** varieties of, 46
* Extra front, 45
* Eye wires, manufacture of, 38
* Face, asymmetry of, 70, 74, 97
* Facing of spectacles, 58
* Focal length of lenses, 76
* Frames (see spectacle frames)
* Frameless spectacles, 39
* Franklin, inventor of bifocal glasses, 23
** glasses, 42
* Geometrical center, 49
* Glass, chemical composition of, 29
** ancient, 17
* Ground bifocals, 44
* Height of bridge, 71
* Hook temples, 38, 95
* Index of refraction, 30 ​
* Inspection and adjustment of spectacles, 76
* Interpupillary distance, 51, 65, 67
* Introduction, 17
* Invention of spectacles, 20
* Irregularity of surface of lenses, 91
* Lateral centering, 55
* Lathe for grinding lenses, 34
* Lens cutter, 35
** oldest known, 18
* Lenses, decentered, 50
** finding focal length of, 76
** forms of, 30
** known to the ancients, 18
** material of, 28
** method of grinding, 34
** neutralization of spherical, 79
*** cylindrical, 80
*** sphero-cylindrical, 81
** numeration of, 33
** proving the strength of, 76
** toric, 37, 63
** tilted, 58
* Locating the optical center, 82
* Lorgnettes, 26
* Maddox pupil localizer, 69
* Marking of gold spectacle frames, 27
* Material of lenses, 28
** of spectacle frames, 26
* Meniscus, 31
* Natural position for spectacle bridge, 57
* Nero, concave jewel used by, 18
* Neutralization of spherical lenses, 79
** cylindrical lenses, 80
** sphero-cylindrical lenses, 81
* New system of numbering lenses, 33
* Normal position of spectacles, 49
* Nose pieces, conformation of, 98
* Numeration of lenses, 33
** of prisms, 84
* Offset guard, 46
* Oldest known lens, 18
* Old system of numbering lenses, 33
* Opticians' lathe, 34
* Optical center, 49
** locating the, 82
* Pebble spectacles, 29
* Periscopic glasses, 36, 62
* Pince nez (see eyeglasses)
* Phacometers, 77
* Plane of the glasses, relation to the visual axis, 58
* Prism diopter, 84
** finding the apex of, 83
** deviating angle of, 84, 89
** refracting angle of, 84, 87
** numeration of, 84
* Prismatic effect of decentering, 51
* Prismetry, 87
* Prescription blank for spectacles, 67
** of eyeglasses, 75
** of frames, 65
* Proving the strength of lenses, 76
* Principal axis, 49
* Principles of spectacle fitting, 49
* Pupil localizer, 69
* Pupillometer, 70
* Refracting angle of a prism, 84, 87
** surfaces, 30
* Rigid frame eyeglasses, 46
* Rock crystal, 18, 29
* Romans, knowledge of lenses among, 18
* Rule for measuring frames, 65
* Saddle bridge, 40
* Salvinus Armatus, 20
* Scratches, specks, flaws, etc., in glass, 90
* Signs used in prescription writing, 32
* Spectacle eyes, sizes of, 42
*** shapes of, 41
** fitting, principles of, 49
** frames, adjustment of, 91
** material of, 26
** marking of gold, 27
** prescription of, 65
** rule for measuring, 65
* Spectacles, component parts of, 27
** bifocal, 42 ​
* Spectacles, care of, 100
** date of invention of, 20
** early references to, 20, 21
** for cosmetic effect, 48
** invention of bifocal, 23
** inspection and adjustment of, 76
** frameless, 39
** facing of, 58
** patterns of, 38
** pebble, 29
** periscopic, 36, 62
** reversible, 40
* St. Jerome's eyeglasses, 21
* Surface, irregularity of, 91
* Temples, distance between, 94
* Temples, manufacture of, 38
** varieties of, 40
* Tilted lenses, 58
* "Tool" for grinding spherical lenses, 35
* Tools for adjusting frames, 91
* Toric lenses, 37, 63
* Transparent glass found in Nineveh, 17
* Trial frames, 69, 74
* Vertical centering, 56
* Visual axis, relation of plane of the glasses to, 58