None
It was fortunate for us that before this country entered the war certain manufacturers had realized the need for optical glass and had erected optical glass plants of satisfactory design. They had, more- over, produced some optical glass of fair quality and had acciunu- lated a good foundation of experience on which it was possible to build. This would not have been the case in 1905. It was also fortunate that there existed at the beginning of the war a scientific research labora- tory with a personnel experienced, not in the manufacture of optical glass, but in the fundamental principles underlying its manufacture. The resources of this laboratory were offered to the Government in the emergency; the oflFer was accepted and the problem of optical- glass manufacture was attacked as would any similar research problem have been attacked. The research investigator is constantly facing new and unexpected problems in his own work, and, as a result, develops resourcefulness and adaptability as well as the faculty of proceeding directly to the essentials of a problem. Shortly after the work was entered upon the more important defects of the existing practice were discerned by the scientists and appropriate remedies were devised to overcome them. It is. only just to admit that in addition to the many other elements essential for the production of optical glass in this country we wer^ favored by good fortune and made the best of it. If a future emer- gency should arise it can hardly be expected that a laboratory of similar experience will be available or that the manufacturers will have builded so wisely beforehand. It is therefore a wise policy for the Government to encourage the manufacture of optical glass in this country by placing orders, during peace times, for optical glass with the manufacturers, thereby building up a reserve stock of good glass against a possible emergency. This policy is being followed by certain other countries. In the case of optical instruments similar arguments are valid; but the fact that new instruments are being devised constantly makes it inadvisable to store large stocks of these instruments. The maintenance of optical repair and manufacturing plants by the Army and Navy is a wise provision, because these function primarily as training schools for personnel against the hour of need. In view, of the highly technical nature of optical instruments both in design, production, and repair it is desirable that a single optical plant with competent personnel serve the entire Army. It is not feasible and would be unwise for the different departments of the Army each to maintain separate optical shops or even separate sec- tions for the design only of optical instruments. The argument has been advanced that in any given branch of the service only the 298 OPTICAL INSTRUMENT SITUATION DURING THE WAR. members of that service have adequate knowledge of the field con- ditions under which it operates and that, therefore, they alone are competent to design the apparatus needed. This is, no doubt, true for much of the material required, but in the case of optical instru- ments special conditions exist which render this plan unworkable. Optical engineers of experience are scarce and unwilling to spend their entire time on the few problems offered by any single branch of the service. The particular problems, moreover, which any Ariny department considers peculiar to itself have much in common with those of other departments; and for each department to maintain a separate section for the design of optical instruments would mean serious and inefficient duplication of work with consequent waste of time and of public money. The fact that both in war time and in peace time the Ordnance Department is responsible for the bulk of the Army optical work and has built up a satisfactory optical shop at Frankfor.d Arsenal with competent personnel indicates that all Army optical work should be done there; also that Frankford Arsenal should be made responsible for the design and production of all experi- mental optical instruments suggested to meiet any new conditions which may arise. The special knowledge of the conditions under which the proposed new instrument is to function can be given by officers or civilians of the special branch of the service which is to use the instrument; but the design of the instrument to sat- isfy these conditions and to be at the same time a manufacturing possibility should be made at Frankford Arsenal as the logical optical organization within the Army. It is imperative that the Army and the Navy each maintain an optical plant not only for the design and test, production, and repair of military instruments, but also for the training of personnel along these lines. It is for this reason especially that no other department of the Government can function satisfactorily for the Army and Navy in this respect, and that the Army and Navy optical shops can not well be consohdated into one large shop. War Department, Office of the Chief of Ordnance, Waahifigion, May, 1921. Form No. 2037. Ed. Mar. 17-21-WO. INDEX. Page. Abbe, E. : New types of glasses 44, 45, 49 Aberration, chromatic 23, 24, 26, 283, 284 Aberration, spherical 24, 25, 265, 268, 283 Aberration, spherical overcorrected 25 Aberration, spherical undercorrected 25 Aberrations, monochromatic 24^ Acetic acid test 222 Adams, L. H.: Optical glass group, 10, 13; strain birefringence, 39, 40, 182, 184, 186; viscosity, 149, 150, 151; temperature distribution, 153; elastic constants, 159; annealing schedule :. - 187 Aiming circles 293 Air bells 33 Alkalinity, natural 221 Alkalinity, weather 221 Allen, E. T.: Optical glass group, 10, 12; chemical analyses, 62, 63, 64, 66, 75; oxidation of arsenic, 105; heat effect 152 Andersen, O. : Optical glass group, 10, 12, 13 ; flint glasses 70 Anderson, M« P. : Fire-control instruments 294 Annealing, classes of 187 Aimealing furnace 180 Annealing of molded or pressed plates 179-189 Annealing period 148-163 Annealing schedules 187, 188 Annealing, state of 38, 41 Apparatus for inspection of strain 207, 208 Artificial star test 266 Astigmatism 26,268,283,284 Autoclave tests 222 AutocoUimation method 274-276, 279, 280 AutocoUimator 271 Axial angle error 270 Axial plane 270 Baking of pot : 116 Barium carbonate 86 Barium crown 45,47,48,53,70,151,153,165,169 Barium crowns, chemical analyses , 60 Barium crown, dense 51, 53, 74, 151, 165, 169 Barium crown, dense, elastic constants 160 Barium crown, elastic constants 160 Barium disilicate 36, 148 Barium flint 45,70,74,151,153,169 Barium flint, chemical analyses 61, 70 Barium flint, elastic constants 160 Batch, filling in 117 Batch mixer, mechanical 113 Batch, mixing of 111-114 Batches 99-110 299 300 B«tdw0, CfMMpntatioB of lOD-UO Battery coMMadcr tefa a co pcg 293 BaoKik A LoMb Optical Co.: Optical gfaw ■aa ufac Hire , », II, 12: prodactioa of optical giaai, 1»; refiactiTity. 41; optical ^wm types. 73, 74: cmbag of ' glaai, 163, 175: aamgaKng of ^sm, 197: gm coosoBiptioB, 288; cootiact forgfan 290 Bansdi^Wia.: Optical glan OHaniigMrtim 11 Bichomky, R.: Optical gian groop, 10; autoclave teste 222 Blehuoger, A. v.: Optical gfa — group , 13; caalprocelaia4ikepoti 87,89 Bloddng , 125 Blockiiig tool 240 Boil : 33 Boil, open. 125 Borate Unit 45 Borate gfaoBM, cfaenoocal anal^nRe 62 Borate optical glan 45,47,50,53,152 Boric acid 86 BoroBiKcate dovrn 45, 70, 73, 151, 153, 165, 169 Bomilicate crmm, chemical analyBea 59 Boroeilicate cidwh, batcfa compoaitioD of 107, 108 Boroailicate cfoim, elastic conetantfl 160 Boroailicate flint, chemical analjnKS 61, 70 Boiren, N. Clark, J. R. : Optical glass compositions 110 Cloudiness 29, 37, 144-148 Collimator 263 Color, freedom from 29, 74-76 Coma 25, 268, 283, 284 Composition, refractivity relations 58 Compressibility, modulus of 160 Compressibility 159, 160 Concave mirror test 199 Cones, Seger 94 Constant deviation method 273 Constringence, optical 43 Convection currents 138, 139 Cooling of glass plates 183 Cooling of melt 137-148 Cooling rate, insulation for 165 Cords 29, CO, 31 Council of Natioiial Defense: Optical glass manufacture 10 Cragoe, C. H. ; Thermal dilatation of glass 152, 159 Cristobalite 148 Crown optical glass 28, 153 Crystallization bodies 37 Crystallization bodies, inspection for 205, 269 Crystallization phenomena 139 Crystallites 29, 36, 37 Crystallites, identification of 147, 148 Cullet 113, 174 Curvature of field 26, 268, 284 Cutting of glass 229-231 Czapski, S. : Strain birefringence 39, 40, 41 Day, A. L. : Optical glass manufacture, 10; heat effect in borate glass 152 Definition ....'. 18, 268 Devitrification. 37 Diameter of entrance pupil 281 Diameter of exit pupil 281 Diamond saws 230 Diaphragm, field of view 20 Diffraction pattern 18 Dimming test 219 Dispersion formulae 55, 56 Dispersion ratios 29, 43 Dispersivity 29, 42, 48 Distortion 26, 283 Dodd, L. E. : Inspection for striae 203 Doelter, C. : Chemical analyses, 59, 66; oxidation of arsenic 105 Double images 283 Dove reflecting prism - 244,270,275-277 Draper, H. : Grinding and polishing 225 Drysdale, C. V. : Inspection apparatus w 286 Eastman Kodak Co. : Ray filters 21 3 Edging of discs 231 Elastic constants 159, 160 Elsden, A. V. : Dimming test 219 39229—21 20 302 INDEX. Page. Entrance port 20 Entrance pupil 20 Entrance pupil, diameter of 2S1 Entrance window 20 Everett, A. ; Chemical analyses, 66; iodoeosin test 220 Everett, J. D.: Chemical analyses, 66; iodoeosin test 220 Exfoliation 158 Exit pupil 20 Exit pupil, diameter of 281 Exner, F. : Strain-birefringence 40 Expansion coefficient 153, 160, 182 External focal length of lens 263-267 Eye distance 282 Eye, far sighted 17 Eye, functions of 16 Eye, iris of 19 Eye, near sighted 17 Feathers. 34, 35, 175, 236 Feathers, inspection for 205 Fenner, C. N.: Optical glass group, 10, 12, 13; glass compositions, 62, 63, 64; furnace temperatures, 94, 95; opalescence in glass, 104; batch composi- tions, 110; glass stirring schedule, 128, 129; forms of silica, 148; pot arch cooling iri3 Ferguson, J. B.: Optical glass group, 10, 13; reflection of light, 77; determina- tion of iron, 79; bleaching of pots 91 i^^eld glasses 293 Field of view 17, 19 Field of view, real and apparent 283 Film on inclosed glass surfaces 223 Film on lens surfaces 284 Film on optical glass surfaces 80 Fining period 117 Fire control instruments 6 Flare 283 Flint, dense 48.53,74,151,165,169 Flint, dense, batch composition of r - 106 Flint, densest 48 Flint, elastic constants 160 Flint, extra dense 48, 52, 53, 54, 74, 151 Flint, light 48, 52, 53, 74, 151, 153, 165, 169 Flint optical glass 28 Flint series 68, 70 Flint series, batch compositions 101-102 Flints, chemical analyses 60 Focus of lens 23 Foerster, F.: Weather stability 219 Focal length of lens 263-267 Folds 175 Folds, inspection for 205 Foucault test. 265 Fracturing of optical glass 161 Frankford Arsenal: Inspection of prisms, 268, 270, 273, 274; optical shop 298 Fraunhofer, J. : Optical glass 121 INDEX. 303 Page. French, J. W. : Grinding and polishing processes ^ 225, 240, 251-254 Fresnel reflection formtda 216 Frink, R. L.: Arsenious oxide. 105 Fry, H. C, Jr. : Lens and prism pressing 177, 235 Fry Co., H. C. : Optical glass manufacture 13 Furnace, annealing 180 Furnace, muffle. 234 Furnace operations 114-134 Furnace operations, schedule of 131 Furnace, pressing 233 Furnace schedule, 24-hour. 132-134 Furnace temperatures 93-98 Furnaces 92-98 Gauss points 264, 266 General Munitions Board: Manufacture of optical glass 288 Geological Siurvey: Raw materials 13, 87 Geophjrsicall^boratory: Optical glass manufacture, 10, 12, 13, 288, 289, 293; chemical analyses, 66, 70; bleaching of pots, 91; batch compositions, 110; glass melting schedule 118, 119, ; photometer 212, 213 Gifford, J. W.: Refractive indices 56, 71 Gill Clay Pot Co.: Melting pots 87 Glazing of pot : 116 Griffiths, C. H.: Flim on glass 223 Grinding and polishing of pressed plates 189-192 Grinding of lenses. 246 Grinding of prisms 236-241 Grinding operations 228, 229 Grinding processes 250-254 Guinand, P. L.: Stirring of optical glass 120, 121 Hall, R. E.: Optical glass group ■. 10 Halle, Bemhard: Grinding and polishing ' 225 Halowax oil 173 Ham, W. R. : Precision milling of prisms 245 Hand stirring 121,122 Harcourt, W. V. : New optical glass types 44, 49 Hardness 29 Hartmann, J. : Optical constants of a lens 264 Hartmann-Tillyer test '. 264 Hazel Atlas Glass Co. : Manufacture of optical glass 13 Homogeneity 29 Hopkinson, F. : Thermal eliastic stresses in glass 153, 182 Hostetter, J. C: Optical glass group, 10, 13, 16; bleaching of pots, 91; rolled optical glass 169 Hovestadt, H.: Dispersion, 55; chemical analyses, 59*, 66; effect of boron, 103; weather stability : 220 Howe, H. E. : Manufacture of optical glass 10 Ihmori, T.: Weather stability. 220 Illumination, intensity of : 17, 18, 19 Image, quality of 22, 284 Immersion method for inspection 172-174, 199-202 Inclusions 29 Inspection of finished optical parts 257-280 Inspection of lenses 260-269 304 INDEX. Page. Inspection of optical glass 194-223 Inspection of optical systems 280-286 Inspection of prisms 26^280 Inspection of raw glass 172 Insulation, rate of cooling 165 lodoeoein test : 220 Jenks, G. F. : Inspection of prisms 270 Jewell, L. E. : Testing of lenses 266 Joint cracks 162 Jointing 162 Jones, H. S. : Dimming test 219 Kellner, H. : Reflection of light ^ . .-. 77 Kerr, J. D. : Strain-birefringence 39 Keuffel & Esser Co.: Manufacture of optical glass, 9.13, 286; optical glass types 73, 74; photometer 212 Keuffel, Carl: Manufacture of optical glass 13 Key industry 296 Kiess, C. C. : Optical glass group 13 Knife-edge test 265 Koenig-Martens photometer 213, 214, 215, 217, 218, 285 Koenig polarization photometer 213 KoUmorgen, F. : Treatment of glass surfaces. .• 77 Laclede Christy Co. : Melting pots 87 Laps 34, 175 Laps, inspection for 205 Lead oxide 86 Lehr, annealing in 188 Lenses, defects in 267 Lens, external focal length 263-267 Lens, focal length of 263-267 Lens, mechanical defects in 262 Lens, optical qualities 262, 263 Lens, physical defects in 260-262 Lenses, cementing 254-256 Lenses, flat .^ 246 Lenses, grinding 246 Lenses, of steep curvature 248 Lenses, photographic 31 Lenses, polishing 246 Lenses, pressing 232-236 Light transmission 209 Light transmission of telescope 285 Linear expansion 160 Liquid inspection 174 Littleton, J. T. : Viscosity of glass 149, 150 Lombard, R. H. : Optical glass group 10, 13 Losses, percentage of glass 191 Magnetic separator Ill Magnification 19, 21 Magnifying power 282 Manufacture of lenses and prisms 224-256 Manufacture of optical glass 81-193 Manufacturing problem 8 • INDEX. 305 Page. Marbles. 157, 158, 162 Martin, L. C: Film on glass 223 Martin, Victor: Manufacture of optical glass 11 Measurement of light transmission 209-21 7 Mechanical defects in a lens 262 Melt, cooling of 137-148 Melting and fining 117 Melting pots 87 Merwin, H. E. : Optical glass group 10 Michelson, A. A. : Striae in optical glass 31 Milky glass 145-148 Milling of prisms 245 Milling operations 228, 229 Molding process 174, 177-179 Molds, pressing 234 Molecular ratios. 106 Molecular weights, table of 106 Monobromnaphthaline 173, 200 Monochlomaphthaline 173-201 Morey, G. W.: Optical glass group, 10, 12, 13; 24-hour melting schedule, 118, 132, 134; annealing of glass 187 Mount Wilson Observatory: Optical training school 295 Muflle furnace 234 Mylius, F. : Weather stability, iodoeosin test 219, 220 National Optical Co. : Chemical analysis 62 Natural alkalinity 221 Naval gun sights , 293 Neumann, C. : Thermal elastic equations 153 Newton interference colors 242, 243 Nodal points of lens 23 Nutting, P. G. : Dispersion formula 56 Objective telescope 21 Onions 157, 162 Opalescence 29, 144-148 Operations, grinding and milling 228, 229 Optical glass, annealing schedules for 188 Optical glass, characteristics of , 28 Optical glass, chemical analyses ., 59-65 Optical glass, coefficient of linear expansion ^ 160 Optical glass, composition of 44 Optical glass, cooling of 154-158 Optical glass, expansion coefficient of 153 Optical glass, modulus of compressibility 160 Optical glass, modulus of rigidity 160 Optical glass, physical and chemical constants 160 Optical glass, strain-birefringence 160 Optical glass, thermal diffusivity 160 Optical glass plant, organization of 81, 82, 83 Optical glass, rate of cooling 165 Optical instrument situation during the war 287-298 Optical munitions, orders for 296 Optical parts, inspection of 257-280 Optical qualities of a lens 262, 263 306 INDEX. Page. Optical syistems, iBepection of 280-286 Ordinary crown 73,151,153,165,169 Ordinary crown, elastic constants 160 Ordinary crowns, chemical analyses , 59 Ordnance Department 13, 288, 290, 294, 295, 298 Orr, H. A. : Navy representative 293 Panoramic sight 31, 244 Parra-Mantois: Optical glass types 39, 49, 51, 71, 72, 185 Partial dispersion ratio 43, 44, 49 Partial dispersions 50, 51, 52, 53 Peddle, C. J. : Optical glass compositions 110 Pentaprism.. 270, 271, 278-280 Personnel 292 Personnel, importance of 81-83 Peters, C. G.: Thermal dilatation of glass 152, 159 Phosphate glasses, chemical analyses 62 Phosphate optical glass •. 45, 50 Photographic lenses 293 Phyacal defects in a lens.. . . ! 260-262 Pittsburgh Plate Glass Co.: Manufacture of optical glass, 9, 12, 13, 289; pro- duction of optical glass, 15; dipsof glass, 41; chemical analyses, 62; optical glass types, 73, 74; melting pots, 89; cooling of glass, 164, 165; liquid inspection 173 Photometer, bench 212,286 Photometer, polarization , : 212, 285 Photometer with neutral tint wedges 212 Pockels, F.: Strain-birefringence 39, 40, 182 Poisson's ratio 159 Polarization photometer 212,285 Polish, lack of 284 Polished surfaces, treatment of 76-79 Polishing of lenses * 246 Polishing of prisms 241-245 Polishing process 242 Polishing processes 251-254 Polishing tool 241 Posnjak, E. : Optical glass group, 10; chemical analyses 63, 64, 66 Pot, baking of 116 Pot, cooling of 130 Pot, glazing of 116 Pot of glass, breaking up '.. 166 Pot, preheating of 114 Pot, removal from furnace 130 Pot, setting of 115 Pot wagon 115 Pots, bleaching of 90 Pots, chlorination of 91 Pots of optical glass, stirred and unstirred 124-137 Pots, open versus closed 89 Pots solution 137 Pot-arch cooling 163, 164 Potasium carbonate 85 Preheating of pot 114 Preparation of glass for lenses^ and prisms 225 / INDEX. 307 Page. Preparation of rav pot glass 170 Pressing defect 30, 34, 35, 175 Pressing defects, inspection for 205, 269 Pressing furnaces 233 Pressing of lenses and prisms , 232 Pressing process 174-177 Principal points of lens ^ 23 Prism, Dove reflecting 244 Prism, resolving power 280 Prism, roof-edge ^ 244 Prisms, grinding of 236-241 Prisms, inspection of 269-280 Prisms, polishing of 241-245 Prisms, pressing 232-236 Prism, right angle 244, 271-275 Prisms, striae in 31, 32 Prism surfaces 270 Production of optical glass 14 Projection methods 202 Pulfrich, C. : Dispersion formula 55 Pyrometer, F6ry radiation 95 Pyrometer, optical 94-98 Quality of image 284 Quartz 148 Rand, C. C. : Chemical analyses 58 Range finders 31, 293 Raw materials 12, 83-87 Raw materials, specifications for • 86, 87 Rayleigh, Lord: Thermalnstress relations, 153* grinding and polishing proc- esses 225, 250, 252 Ream 29, 30, 32, 169 Reflecting power ; i , 76-79 Reflectivity 76 Refractivity 29, 41, 46, 47 Refractive index, variations in 72 Repair shops 297 Resolving power 17, 20, 21, 268, 269 Resolving power of prisms 280 Resolving power of telescope 283 Reticules 32 Ribbons 29 Rigidity, modulus of 160 Ritchey, G. W. : Grinding and polishing process, 225, 241; optical training school 295 Roberts, H. S.: Optical glass group, 10,13; bleaching of pots, 91; annealing period, 153-158; cooling of optical glass melts 164, 165, 169 Roberts, E. H.: Viscosity of glass 149, 150 Roberts, 0. : Dimming test 219 Rolled optical glass 32, 167-170 Roof-angle prism 270, 271, 277, 278, 295 Roof-edge prism 244 Rosenhain, W. : Grinding and polishing processes 250 Rough grinding '. 191 Rubens, H. : Dispersion in optical glasses 45, 46, 52 308 INDEX. Page. Ryland, H. S. : Film on optical glass '. 223 Sand 84 School for training operatives 295 Schott, O.: Strained glass 41; new types optical glass 44, 45, 49; strain bire- fringence 153 Schott & Genossen: Types of optical glass 39, 51, 56, 57, 66, 67, 71, 72, 163, 185 Schulz, H.: Thermal-stress relations 153, 182 Seeds 33 Seeds, inspection for 205, 269 Sellmeier: Dispersion formula 55 Setting of pot 115 Side angle error 270 Signal Corps 290 Silica 147 Sillimanite 141, 148 Simon, 11. T. : Dispersion in optical glasses 45, 46, 52, 54 Sine condition 24, 25 Sizes of blanks 226 Skimming -. 120 Smith, T. T. : Inspection for striae, 203; resolving power 283 So, M. : Viscosity of glass 149 Sodium carbonate 86 Spectrum, secondary 26, 108 Spencer I^ens Co.: Manufacture of optical glass, 9, 12, 289; production of opti- cal glass, 215; chemical analyses, 62; types of optical glass, 73, 74; pot arch cooling 163 Spherical zones 25 Spherulites 36 Spherulites, radial 37 Stability, chemical 29 Stability of optical glasses 218 Stability, physical « .• 29 Stirring machine 122,123,126 Stirring process 120, 123-129 Stirring rod 122 Stokes, G. G. : New types of optical glass 44 Stones 29, 34, 35, 36 Stones, inspection for 205, 269 Strain. 29, 37 Strain, inspection for 206 Strain birefringence 39 Strain birefringence 160 Striae - 29, 30, 31, 38 Striae, inspection for 195-205, 269 Taylor, H. D. : Treatment of glass surfaces 76 Taylor, W. H. : Optical glass group, 13; liquid inspection 173, 199, 200 Telescope, lens system of - 16, 19, 22 Telescope, light transmission 285 Test plate.. -^ 267 Therelfall, R. : Grinding and polishing operations 225 Thermal diffusivity 160 Thermo-element 94, 186 Threads 29, 31 INDEX. 309 Tillyer, E. D. : Optical constants of a lens 2ft4 Toepler method 197 Tolerances 257-259, 290 Tolerances, prism angle 270 Tool, A. Q.: Viscosity of glass, 149, 150; heat effects 151,152 Toughness 29 Training school 295 Transmission of optical instruments 218 Transparency 29 Transparency of glass 209 Tridymite 148 Trimming raw optical glass 171 Turner, W. E. S. : Opalescent glass, 104; optical glass compositions 110 Twyman, F. : Viscosity of glass, 149-151 ; annealing of glass 184, 185 Types of optical glass ^ 73, 74 Vacumn bubbles 33, 139 Valasek, J. : Viscosity of glass, 149, 150; heat effects 151, 152 Van Auken, W. R. 