Grid circuit impedance, electron tubes, S351. modulation, radiotelephony, S423.

Grog in fire-clay bodies, T104.

Ground, capacity of inductance coils to, S175, S427. capacity of inductance coils to, S430.

connections for electrical systems, T108. effect on antenna resistance, S189, S257. Grounding, H3, H4.

effect on capacity of inductance coils, S427. effect on capacity of inductance coils, S430. electrical equipment and lines, C49.

of electrical circuits, M58.

Ground-speed indicators, T237.

Grounds, lightning, T56.

Group of objects, detecting changes in, S392. Gum arabic, qualitative tests and quantitative determination, T67.

Hardening Portland cement with Cal, T174.

secondary, of high-speed steel, S395.

Brinell and scleroscope, TII.

related to grain size of steels, S397.

low-carbon, open-hearth steels, T203.

methods of measuring, T1.

red, of high-speed steel, $395.

Hardness, M62.

electrical insulating materials, measurement, S471.

Hardware, builders', R18.

Harmonic analysis of waves, S203.

Harmonics, electron tube generators, S355.

effect of phase upon acoustic quality, S127. Harness leather, physical properties, T160. Hartmann test for lenses, S311, S494.

Head protection for industrial workers, H2.

Head resistance of radiators, T211.

Heads and eyes of industrial workers, national

safety code for protection of, H2.

Heaped bushel, Cro.

Heat calorimetry, S503.

dissipated by automobile tires, T213.

etching to reveal microstructure of metals, S356. effect upon celluloid, T98.

insulating properties of fire-resistive materials, T130.

tile, T120.

value, data, T269.

discussion, T269.

tests for textiles, T269. insulation (textiles), T266. latent, of fusion of ice, S209.

of pressure variation of liquid ammonia, S314. of vaporization of ammonia, S315.

measurements, C55, S501, S503.

see also reports, annual, of the director.

of combustion, S230.

of fusion of ice, S200, S248.

resisting alloys of nickel, C100.

specific, of calcium chloride solutions, S135.

of ice, S248.

of liquid ammonia, S313.

treatment, carbon steel, T206.

duralumin, S347.

effect of, on magnetic properties of iron carbon alloys S463.

effect upon copper and its alloys, $410.

upon drying clays, S151.

upon insulating materials, S352.
high-speed steel, S395. T228.
iron-carbon alloys, S463.

light aluminum casting alloys, T139.
mercurial thermometers, S32.
molybdenum, S332.
preliminary, of clays, Tr.

bibliography, C81.

emission spectrum, S191.

gas, S89, S176.

lines, intensity, S146.

Spectrum, S302.

Helmet-shaped rubber ice bag, C228.

Hertz formula for contact area, ball and roller bearings, T201

Heterochromatic photometry, S238.

"average eye" for, S299. Heterodyne reception, C74

Heterogeneous brasses, mechanical properties, S321. Heusler magnetic alloys, S38.

Hexagonal coils, inductance, S468.

Hide, different parts, relative wear, T147.

wear resistance at different depths, T166. High-boiling mineral oils, S160.

fire porcelain glazes, T196.

High frequency amineters, S206. circuits, S158, C74.

energy losses, S190, C74.

current, measurement, S140, S158, S206, C74. sources, C74.

electrical oscillations, S95.

oscillations from the electric arc, S60.

scale, S143.

extrapolation, S260.

tensile tests of boiler plate, T219.

thermometry, S124.

treatment of high-speed steel, S395.

tension magneto, theory of induced voltage, S424.

History of standard weights and measures, S17, M64. Hollow building tile, T120.

tile and concrete floor slab, test of, T220, C261. slab, loading test, T236.

walls, strength of, T238.

Home, how to own your own, BH4.

Homemade radio receiving sets, C121.

Honey, solubility of sugars in, T259.

Honeycomb inductance coils, S455.

winding, S449.

Hooks, T260.

Hopper scales, hand operated, C199.

Horizontal coils, field radiation of, S431. intensity of lamps, S43. S63.

Horsepower, relation to kilowatt, C34.

Hose couplings, M42.

and fittings for fire service, C50.

fire, cotton rubber-lined, C114.

oil suction and discharge, C209.

threads, C50, M42.

Hosiery, T253, C149, C169. box designing, T253. measurement, T253. boxes, T253, C169. measurement, C149. packing, T253.

weights and measures, M39.

How to build electron-tube detector, C133.

How to own your own home, BH4. Humidity, control tank, S471. influence on resistances, $73. measurements, C55.

Hydrated lime, C153.

for cooking paper rags, C96.

for glass manufacture, specification, Cr18. for structural purposes, C204.

for use in the purification of water, Ca31. recommended specification for, for use in the manufacture of calcium arsenate, C203.

recommended specification for, for use in the manufacture of sugar, C207.

U. S. Government master specification for, for structural purposes, C204.

Hydration of Portland cement, T43.

Hydrogen, analysis by thermal conductivity method, T249.

atomic weight, S77.

decarburization of ferrochromium by, S448.

ion concentration, S178, S364.

indicators, S286.

lines, intensity, S146.

sulphide in gas. T41.

Hydrolysis of sodium oxalate, S178.

Hydrometer scales, standard Baumé, C59.

Hydrometers, master scales, C19.

testing, C16.

Hydrostatic tests of steel tanks. T243.

Hypergeometrical series, mutual inductances of coaxial circles, S138, S169.

Hypersensitizing without the use of ammonia, S422.

Hysteresis, in measuring instruments, S328. galvanometer, S185.

thermometric, S185.

values from high magnetizing forces, S383.

Ice bags, rubber, C227.

I

gas, determination of ammonia, T34.

specifications, T14.

sulphur in, T20.

Illumination from radiating disk, S263.

Image brightness with optical instruments, C27.
Impact, T289.

excitation, radio-frequency current, S95.

strength, electrical insulating materials, measurement, S471.

Impedance, input, of three-electrode vacuum tube, S351.

Improved folding of men's hosiery, T253.

packing of men's hosiery, T253.

Incandescent lamps, efficiency, measurement, S30. mean horizontal intensity of, S43, S63. specifications, C13.

temperature and radiation, S40.
testing, life, S265.

and capacity, distributed, in secondary coupled circuit, S126.

see also Reports, annual, of the director. Anderson's method, measurement, S14. calculation of mutual and self, S93, S169, S320. circle and a coaxial single-layer coil, S56, S169. circles, S75, S169, C74.

coaxial solenoids, mutual, S58, S59.

coils, S36, S41, S42, S47, S56, S58, S59, S74, S138. capacity, S175.

distributed capacity, S427.

electrical oscillations, S326.

natural frequency, S326.

wave length, S427.

oscillations, S326.

tape, rubber, C230.

Insulating materials, electrical, T216.

study of the seasonal variation of radio-fre

quency phase difference, T284.

thermal expansion, S352.

volume and surface conductivity, S234. pipes to prevent electrolysis, T15. properties, measurement, S471.

lead, $377.

Interfacial tension of oils, T223.

Interference, S477.

apparatus, S507.

bands, oscillatory, S150.

change in order of, S199.

measurements in spectra of argon, krypton, and
xenon, S414.

of wave lengths, S142, S179, S251, S274, S302,
S329, S414.

methods for standardizing gauge blocks, S436.
testing gauge blocks, S436.

phenomena photography, S441.

Interferential dilatometer, S365.

Interferometer, gas, calibration, S316.

used in gas analysis, T131.

Interferometry, see Reports, annual, of the director.

Intergrating sphere, photometric, S447.

Interior varnish, specification, C117.

Intermittent testing, T171.

Internal stresses in brass, T82.

resulting from welding, T84.

in brass tubing, T285.

International adoption of electrical units, S102.

system of weights and measures, M2.

system of electric and magnetic units, S292.
unit of light, C15.

volt, value, C29.

Invar, properties, C58.

Inverse fading, of radio signals, S476.

Inverse-rate method for thermal analysis, S336.

Inverse-rate method of thermal analysis, recording
chronograph for, T230.

Invert sugar, "solubility" of, T259.

*Investigation of weights and measures by Bureau
of Standards, M9.

Investigations, radiometric, of spectra, S45.

Iodine number of linseed and petroleum oils, T37.
voltameters, S218.

Iodine pentoxide apparatus for carbon monoxide,
T222.

spectrophoto-electrical properties, S462.

Ionization, atomospheric radio transmission, S159,
S226.

potentials, electrons in cadmium vapor, S317.
lead and calcium vapors, S368.

six nonmetallic elements, S400.

Iridium arc spectrum, S499.

reflection, S45.

spectrographic examination of, S483.

Iron, alloys with carbon and manganese, S453.

analysis, T33, T118, C14.

arc, spectrum, S324, S478, S479.

bimetallic wires, inductance, S252.

car wheels, thermal stresses in, T209.

carbon alloys, S266.

effect of manganese on microstructure of, S454.

magnetic properties of, S463.

thermal analysis, S484.

cast, graphitized upon annealing, T129.
locomotive-cylinder parts, T172.
thermal expansion of, S433.
wet process enameling of, T246.
clad galvanometer, S188, S229, S244.
colorimetric determination of, S53.

core transformer, S449.

Iron, alloys with carbon and manganese-Contd.
critical ranges, S213, S296.

demagnetization in magnetic testing, S78.
determining carbon in, T33.

determination of nitrogen in, S457.

effect on determination of iridium, $483.
electrodeposition of, S266.

electrolytic, thermal expansion of, S433.
electrolytically corroded in soils, T25.
etched by ammonium persulphate, S402.
group elements, melting points, S62.
in brass, T221.

microstructure, T221.

in cast red brass, T221.
inclusions in brass, T221.
loss equations, S164.

losses in transformers, S88.

microstructure at high temperatures, S356.
ores, analysis, C26.

oxide and iron-hydroxide paints, specification,
C93.

emissivity, S249.

Kitchen card, M39.

Knit goods standards, C149.

tubing, laundering, T273.

Koepsel permeameter, S228.

Kolster decremeter, S235. C74.

König's data, S154.

Koppers type oven for coking Illinois coal, T137.
Krypton spectrum, S414.

Life, frosted lamps, S61, S72. lamps, C13.

machine-gun barrels, T191.

testing of incandescent lamps, S265.

Light alloys of aluminum, properties, C76. aluminum casting alloys, T139.

filters, S191, T217.

radiometric investigation, S168.

forces in polariscopic measurements, S34. measurements, C55.

mechanical equivalent, S305.

mercury arc, S128.
oil fractionation, T140.
reflection, S391, S405.

sources, monochromatic, S44.
tubes, S51.

unit, international, C15. velocity, S65.

waves, length, S251.

in standardizing gauges, S436. weight duck, C166.

see Reports, annual, of the director. Lighthouses, radio beacons, S428. Lightning protection, T56.

Lime, C150, C151, C152, C153, C201. bags of paper, T187.

for use in manufacture of sulphite pulp, C144. recommended specification for, for use in the manufacture of sugar, C207.

Limitation of varieties of paints and varnishes, LI. Line construction, H3.

rules for electrical workers, C49.

Linear conductors, inductance, S80. curves, S388.

measures, C2, C61.

Lines, spectrum, S34.

Linoleum, battleship, C191.

plain, inlaid and printed, Cr90.

Linseed oil, affected by pigments, T71.

comments on, T274.

density and thermal expansion, T9.

infra-red spectral transmission, S168, S418.

specification, C82.

Linseed oils, iodine number, T37.

Liquefaction of air, S123.

Liquefier, Hampson, S123.

Liquid air plant, see Reports, annual, of the direc