bluuebunny/crossref_metadata_2025 huggingface dataset:
A REVERSING AND SHORT-CIRCUITING SWITCH FOR USE IN HYSTERESIS MEASUREMENTS
Authors: Smith Arthur Whitmore
Published: February 2005

A switch for hysteresis measurements is made by building an additional jaw at each end of the usual double pole, double throw, reversing switch. After reversing the current, one of the switch blades enters the added jaw, thereby short-circuiting an adjustable part of the circuit and increasing the current to its fixed maximum value. This makes it possible to stop at any chosen point on the hysteresis curve, and to carry the steel in a single step from this point to one tip of the hysteresis loop. A ratchet and pawl on the handle of the switch insures that the steel is carried through the complete hysteresis cycle each time.
HEAT LOSS FROM DEWAR FLASKS
Authors: Kenneth S. , Cole Robert H.
Published: February 2005

Dewar flasks obey Newton's law of cooling when the contents are adequately stirred. From cooling curves the water equivalent has been determined and the heat loss coefficient in calories per hour degree C difference has been found to be independent of the volume of contents between 50 percent and 90 percent capacity. For twin calorimetric purposes, flasks may be equalized by variation of the volume of contents as suggested by Hill, but it has been found that the best flasks are quite uniform and require but little compensation. The half-pint flasks used have a heat loss of about 12 calories/hour degree C difference and water equivalent of about 36 cc.
THE MEASUREMENT OF X-RAY INTENSITIES AS FUNCTIONS OF VOLTAGE, UP TO 180 KV
Authors: Webster D. L. , Hansen W. W. , Duveneck F. B.
Published: February 2005

The measurement of intensity of an x-ray line presents two sets of technical requirements, quite different, according to whether the intensity is to be compared with those of other lines at the same voltage or of the same line at other voltages. The latter set of requirements is discussed here, with a description of a tube designed to meet them. This tube is built of steel and Pyrex, with several sections of each, permitting a variety of high-voltage connections for special purposes related to possible sources of error. To prevent the deposition of carbon and tungsten on the target, the pumping speed is made very high, especially for grease vapors. The detection of carbon, and rough measurement of its retardation of the cathode rays, is accomplished by one of the special changes of connections. To minimize the effects of such positive ions as may be present in spite of the high pumping speed, the tube has a special form of cathode. And to measure the possible amount of error due to such ions, another of the special connections transforms the cathode-ray chamber of the tube into an ionization gauge. Finally a third change of connections makes it possible to wear out the sources of minute field currents, that would otherwise cause errors in x-ray intensity measurements.
A MECHANICAL AID TO THE ANALYSIS OF COMPLEX SPECTRA
Authors: Harrison George R.
Published: February 2005

A simple machine is described which quickly and automatically records on a chart the wave-number intervals between each line in a spectrum and every other line within any desired range. Small rectangular holes are punched in a black paper tape, their positions corresponding to the wave numbers of the lines on a linear scale. This operation is rapidly carried out by means of a magnetically operated punch, working on the tape which passes over a cylinder from which wave numbers can be directly read off. The punched tape is then fed from a reel through a simple device which causes it to return on itself after passing for one meter directly over a sheet of bromide paper which is moving at right angles to the tape at a fraction of the speed of the latter. The returning tape, after passing over itself for a meter, is pulled between two rollers and stored on a reel. A set of lights is hung over the doubled tape, and whenever two punch marks come into coincidence a small rectangle on the photographic paper is exposed. Fairly high tape speeds can be used, so that a complete spectrum can be recorded in a few moments. On developing the record, the photographic paper, 40 inches wide and as long as needed, is found covered with small rectangular dots; the abscissa of each rectangle gives the interval between the two dots producing it, while its ordinate gives the actual wave number of either. Suitable marks having been punched into the tape before and after the spectrum, the calibration of the interval and wave-number scales to compensate for any shrinkage of the record is automatically made. Those lines having any given separation in the spectrum can be quite readily picked out from the multitude of dots by means of a straight-edge. By suitably varying the scale used for plotting wave numbers on the tape, the width of the punch marks, and the ratio of tape speed to paper speed, each type of spectrum can be treated in the most suitable manner. Where very large intervals must be recorded while a fairly open scale is still used arrangement is made for keeping a desired constant amount of slack in the returning tape, so that on one record all intervals between 30 and 2030 cm−1 might appear, on another 2000 to 4000, etc. Provision can also be made for determining from the appearance of a dot the approximate intensities of the lines combining to produce it.
TELLURIUM-BISMUTH VACUUM RADIATION THERMOCOUPLE
Authors: Cartwright C. Hawley
Published: February 2005

A simple method of constructing delicate radiation thermocouples with gold leaf receivers is described in detail. A tellurium wire ¼ mm long could be easily welded to the receiver by using a condenser discharge. The thermoelectric power of tellurium in its β-modification against bismuth is about 600 μv/°C. The thermocouples are about three times more sensitive than those made with bismuth alloy wires. Some methods for evacuating and permanently evacuating the thermocouples are given.
SENSITIVE ELECTROSCOPES
Authors: Lukens Charles
Published: February 2005

Three electroscopes are described whose electrodes are: (I) a single fiber repelled from a forked wire, (II) a Schonland electrode hollowed to increase the sensitivity, (III) a Schonland electrode, also hollowed, but with the mirror hung on a single gold leaf suspension and rotating on a nearly vertical axis. The deflections produced by the emission of an α particle, as a consequence of which about 105 ions were collected, were approximately: for type I, 5 eyepiece scale divisions; type II, 7 mm; type III, 20 mm. A method is given for determining the charge sensitivities of certain electroscopes.
A LECTURE-DEMONSTRATION OSCILLOGRAPH
Authors: Hansen William W.
Published: February 2005

A cathode ray oscillograph with a linear time scale is described. The apparatus is designed for demonstration use and will illustrate either 60 cycle or transient phenomena.
A NEW METHOD OF MEASURING CONTACT POTENTIAL DIFFERENCES IN METALS
Authors: Zisman W. A.
Published: February 2005

A new method is described for measuring the contact potential differences between dissimilar metals. It enables one to measure the p.d. to 1/1000 volt in a few seconds of manipulation. An apparatus is described for studying metals in air and another is described for high vacuum work.
A Complete Geiger-Müller Counting System
Authors: Lifschutz Harold
Published: February 2005

Constructional details are given of a complete Geiger-Müller counting system consisting of a stabilized high voltage supply, Neher-Harper coupling circuit and vacuum-tube scale-of-eight feeding a Cenco counter stage. The system is entirely a.c. operated. Its resolution time of 6.5×10−6 second allows it to follow the G-M circuit without counting losses. The counting losses in the Cenco counter stage are negligible for random input rates to the system up to 20,000–30,000 counts a minute.
The Synthephone
Authors: Culver C. A. , Williams D. T.
Published: February 2005

A new form of apparatus has been developed by the use of which it is now possible to synthesize musical and other sounds from their elemental components. The basic unit in this equipment is an electrostatic alternator. The new device, which is useful in the study of problems in the field of musical acoustics, has been named a ``synthephone.''
Vacuum Tube Circuit to Measure the Logarithm of a Direct Current
Authors: Meagher Ralph E. , Bentley Edward P.
Published: February 2005

A circuit, using a single tube, and having an output voltage which is proportional to the logarithm of a direct current input, is described. The input current range extends from less than 10−7 ampere to 10−5 ampere if a closely linear logarithmic relationship is desired; and from 10−8 to 10−3 ampere if only an approximately logarithmic characteristic is necessary. Because the circuit depends for its operation on a fundamental physical law (the Maxwellian distribution of velocities of the thermoelectrons emitted from a hot cathode), its characteristics are constant and predictable.
Curved-Crystal Ionization Spectrometer for X-Rays
Authors: Stephenson S. T.
Published: February 2005

The ionization method is applied to the curved-crystal spectrograph. The ionization chamber is mounted behind a slit moving in the focal cylinder. Tests on the Mo Kα1α2 doublet indicate better intensity than that obtainable with the usual Bragg spectrometer for a given resolving power. The best line widths are not as narrow as those obtainable with a double crystal spectrometer.
Electrically-Driven Magnetically-Supported Vacuum-Type Ultracentrifuge
Authors: Beams J. W. , Black Sheppard A.
Published: February 2005

A large rotor or centrifuge, an armature, and a small iron rod are anchored coaxially one above the other, in the order named, on a small flexible shaft. The shaft passes through a vacuum-tight oil gland which seals a vacuum-tight chamber surrounding the large rotor. A direct current which energizes an electromagnet situated vertically above and coaxial with the iron rod is adjusted so that the pull on the iron rod is slightly greater than necessary to support all of the rotors. The extra lift is balanced by a slight thrust against the upper end of the shaft by an oiled bronze stop in the pole piece of the electromagnet. The adjustments are made to maintain a small air gap between the rotating iron rod and the stationary pole piece. The rotors are driven by a piezoelectrically-controlled a.c. through the field of a single-phase induction motor which surrounds the armature. Six-inch centrifuges have been spun to over 1000 r.p.s. at very constant speed.
A Periodic Wave Analyzer
Authors: Klemperer Hans
Published: February 2005

A wave analyzer is developed by replacing all moving parts and contacts of the original Joubert disk by electronic means. The wave analyzer is able to provide a point by point delineation of such wave shapes as are not easily accessible to the oscillograph. Circuits and operation of the wave analyzer are described and two examples of application in the field of gas discharge research are given.
The Design of an Accurate McLeod Gauge
Authors: Rosenberg Paul
Published: February 2005

All McLeod gauges heretofore constructed with large volumes and fine capillaries have failed to attain the sensitivity, precision, and accuracy which should be expected from the compression ratios. This is due to certain experimental difficulties which are enumerated. Description is given of a large McLeod gauge whose methods of construction eliminate all these difficulties and whose high sensitivity, precision, and accuracy are fully comparable to the gauge's compression ratio of 2.4×10−7. The methods of construction can be applied advantageously to small as well as to large McLeod gauges. At pressures of 10−2, 10−3, 10−4, and 10−5 mm of mercury, the precision of this gauge is 0.2, 0.6, 2, and 6 percent, respectively.
Thermoelectric Measurement of High Temperatures in Pressure Apparatus
Authors: Birch Francis
Published: February 2005

The effect of pressures up to 4000 kg/cm2 upon the thermal electromotive force of chromelalumel, and of platinum-platinum-10 percent rhodium couples has been observed for hot-junction temperatures up to 580°C. Within this range, the electromotive force of the chromelalumel couple is independent of the pressure, to within about 10 microvolts, or one-quarter degree. An appreciable and regular effect is found for the platinum-rhodium couple, amounting to a decrease of the electromotive force by about 16 microvolts, or 1.8°C at 500°, for a pressure of 4000 kg/cm2. The results are presented as curves showing the decrease of electromotive force as function of temperature and pressure.
Zigzag and Helical Springs; Elastic Properties of Molybdenum
Authors: Tawney G. L.
Published: February 2005

A ``zigzag'' type of spring for supporting current-carrying filaments is described and compared with the tungsten helical type of spring. The zigzag spring is particularly useful when a combination of high current-carrying capacity and low spring constant is desired. Designs and stress analyses are deduced both for the helical and the zigzag spring, to meet a wide range of requirements. An approximation is given for the elastic limit of molybdenum and the rolling and annealing of molybdenum sheets for tube parts are discussed.
A Recording Generating Voltmeter for the Study of Atmospheric Electricity
Authors: Workman E. J. , Holzer R. E.
Published: February 2005

A generating voltmeter type automatic electric field recorder designed for continuous measurement of surface electric fields in thunderstorms is described. The performance of the instrument in the field under thunderstorm conditions is discussed. The application of this instrument to the study of the normal potential gradient of the earth is suggested.
On the Theory and Use of Ross Filters
Authors: Kirkpatrick Paul
Published: February 2005

Resolving power, preferred thickness and balance errors of Ross filters for x-ray monochromatization are discussed. It is theoretically impossible to balance two filters of elementary composition because of scattering, L limits and K jump, even if the absorption coefficients of the two filters vary similarly with wave-length between the limits, which is not known to be the case. It suffices, however, to obtain good balance for wave-lengths near the pass band since others longer and shorter may be relatively reduced by pre-filtration through a filter whose composition is the same as that of the high atomic number member of the balanced pair. The K jump balance error may be completely removed by adding a slightly absorbing filter of low atomic number to one member of the pair. By employing a specially designed ionization chamber Ross filters may be used simultaneously instead of alternately and a considerable gain in speed and accuracy achieved.
The Technique of High Intensity Bombardment with Fast Particles
Authors: Kurie Franz N. D.
Published: February 2005

Recent improvements in cyclotron technique have led, in the case of the 37″ cyclotron at the University of California, to the utilization of beams of such intensity that nearly a kilowatt of power must be dissipated in the target. To maintain high operating efficiency it is desirable that targets should be bombarded in elementary form rather than as compounds, and that the cyclotron vacuum chamber should be protected from the debris of bombardment at all times. The former requirement puts a severe limitation on the designer because many elements are neither refractory nor are they good heat conductors. The second requirement necessitates that a thin metal window be used to isolate the target from the vacuum chamber, because most elements sublime or spatter in one way or another no matter how well cooled they may be. To meet this situation a bombarding chamber has been developed (a ``bell-jar window''). It consists of a rectangular copper box with one end closed by a water-cooled copper plate carrying the target and the other by a thin metal window. The window end is bolted to the cyclotron's target orifice and the interior of the box is filled with hydrogen or helium at a pressure of a few centimeters. The presence of the gas serves to keep the window cool, to keep the target from being damaged by the beam and to protect the cyclotron in the event of a sudden failure of the window. The metal windows are supported on a grid of elongated holes which has a geometrical aperture of about 93 percent. The target plate is heavily knurled and the element being bombarded may either be fused on it or pressed into the knurlings with a spatula. The surface of the target can further be protected by covering it with thin gold foil. With this arrangement it has been found possible to bombard red phosphorus, sodium metal, lithium metal and many other difficult targets with the full intensity of the cyclotron.
A Portable Motor-Driven Apparatus for Depositing Built-Up Molecular Films
Authors: Gregg S. J. , Widdowson E. E.
Published: February 2005

A description is given of a simple motor-driven apparatus for the deposition of built-up molecular films on plane solid surfaces. Special features of the apparatus are its portability and simplicity of construction, and it is suitable both for lecture demonstrations and for research.
On the Theory of the Electrostatic Beta-Particle Energy Spectrograph. II
Authors: Rogers F. T.
Published: February 2005

This paper is a discussion of the effects, on the use of the electrostatic energy spectrograph for charged particles, of the field distortions at the edges of the spectrograph plates and in between the plates. These effects are evaluated and shown not to be negligible in measurements of highest precision. It is shown how, by properly locating the source and detector of charged particles, to eliminate these effects to the extent of a first approximation. The discussion is carried through for only one particular form of spectrograph plates, but the modifications necessary to make it applicable to any other form of spectrograph are adequately pointed out.
A Thermostat for Room Temperature Control
Authors: Green J. B. , Loring R. A.
Published: February 2005

A simple method for construction of an ether-vapor thermostat is described, and a relay control system for accurate temperature control of rooms is given. With this arrangement, the temperature at specified localities in a room may be kept constant to less than 0.05°C over long periods of time.
Rugged Quartz Membrane Manometers of Small Volume
Authors: Kenty Carl
Published: February 2005

Fused quartz membrane manometers, used as null instruments, have been developed for measuring pressures of Hg, or other vapors (or gases) from a few centimeters of Hg to 50 atmospheres, with an accuracy of the order of 0.1 percent. The membranes are clear fused quartz disks, plane polished, 0.1 to 0.5 mm in thickness, and 0.5 cm to 2.5 cm in diameter. These are sealed onto fused quartz heads, either plane or slightly concave. In the first case, the motions of the diaphragms are magnified mechanically by a three-legged rocker, the two outer legs of which rest on fixed bearings and the middle one of which rests on the diaphragm. The three legs being only slightly out of line, a high magnification (up to 6000) is obtained when a mirror and a long light path are used, or a pointer and a microscope are employed. In the second case, interference fringes set up between the diaphragm and the near-by slightly concave quartz surface indicate the motions of the former. Volumes as small as 4 mm3 have been attained, and all-quartz manometers, remarkably constant in calibration, are operable at temperatures of 800°C, or higher. Certain forms of these manometers are extremely rugged and free from explosion hazard at high pressures. These manometers are being used to measure the operating pressures in high pressure (H-type) Hg lamps.
A Direct-Current Amplifier Employing Negative Feedback for Measuring Stellar Photoelectric Currents
Authors: Heidelberg Q. S. , Rense W. A.
Published: February 2005

In this paper a direct-current amplifier is described which employs negative feedback for the measurement of small stellar photoelectric currents. A General Electric type FP-54 electrometer tube is used in the input stage to give maximum sensitivity. The output voltage is fed back negatively into the input stage and the amplifier locks in a condition of equilibrium. In this condition the output voltage matches the input voltage with a tenacity proportional to the voltage gain of the amplifier before the feedback is applied. A high gain stage employing one type 1N5-G tube as a load for another type 1N5-G tube supplies a voltage gain of about 1500. The output stage uses a type 1C5-G tube connected as a triode. The output meter used is a Weston portable microammeter with full scale deflection of 50 microamperes. A 1900-ohm resistance is used in series with the meter to give full scale deflection for 0.1 volt. Thus with an input resistance of 2×1010 ohms, a photoelectric current of 5×10−12 ampere gives full scale deflection.
An Improved Apparatus for the Direct Measurement of the Absorption of Sound in Gases
Authors: Leonard Robert W.
Published: February 2005

An improved apparatus for the direct measurement of the absorption of sound in gases has been designed, built, and tested with the highly absorptive gases, carbon dioxide and nitrous oxide. Measurements are made of the sound pressure by a microphone as it is moved away from a piston source vibrating in a large baffle. The resulting pressure-distance curves are recorded photographically and yield the absorption coefficient. Reflections from the walls of the cylindrical measuring chamber are reduced materially by specially designed glass baffles. The source is the end of a magnetostrictive rod driven by an improved Pierce-type oscillator with a frequency range of 11.3 to 112 kc. A magnetic drive is employed to move the microphone, eliminating packing glands and providing a constant volume measuring chamber. The microphone was built up from a single bender-type Rochelle salt bimorph element. A milliampere meter movement is used in the recorder, making possible comparatively rapid recordings.
Technical Requirements in the Determination of Absorption Spectra by the Ultraviolet Microscope
Authors: Cole P. A. , Brackett F. S.
Published: February 2005

To overcome the difficulties and limitations of earlier methods for obtaining absorption spectra of detailed microscopic structures, it has been found necessary to impose more rigid demands upon the monochromator and to introduce improvements in densitometry. The optical properties of the microscope and the spectral properties of the source together determine the requirements which must be made upon the monochromator. These requirements are analyzed and a convenient method of quantitative densitometry is described together with the results of a simple test of this method.
An Electrical Method for Compounding Sine Functions
Authors: Maxwell Louis R.
Published: February 2005

An electrical device is described for evaluating the series ΣAi sin aix. For each term in the series there is constructed one compounding element composed of three coils; a long solenoid acting as a primary (60-cycle a.c.) within which are mounted two short secondary coils, one a rotor (order of 1/5 r.p.m.) and the other a stator. The mutual inductance between the primary and rotor varies as the sine of the angle aix of rotation while the primary current is held proportional to Ai. The vector sum of the peak voltages induced in the rotor and stator varies about a constant value proportional to Ai sin aix. Thus the variations of the resultant voltage from all of the elements about a constant value are proportional to the sum of the series. A record of the sum is made on photographic paper by means of a vacuum tube voltmeter circuit. Satisfactory tests have been made on a machine containing two elements. The application to structure determinations of gas molecules by electron diffraction is presented.
Generating Voltmeter for Pressure-Insulated High Voltage Sources
Authors: Trump J. G. , Safford F. J. , Van de Graaff R. J.
Published: February 2005

A description is given of a generating voltmeter suitable for a voltage source insulated by compressed gas. The calibration is linear and the design simple in that neither amplification nor mechanical commutation is required. The paper discusses the principle of operation, the construction, calibration, and sensitivity, and tests indicating that the influence of corona on the voltage readings is negligible.
An Experimental Condenser for Determination of Dielectric Constants of Liquids
Authors: Williams D. T. , Copeland C. S.
Published: February 2005

A cylindrical condenser has been so designed that it may be filled to a variable height with a liquid whose dielectric constant is desired. From the variation of the capacitance with the height, and a knowledge of the dimensions of the cylinders, one can make a determination of the constant that is free from errors due to stray capacitances. An analysis of the apparatus seems to indicate the method is capable of high precision.
An Apparatus for Determining the Orientation of Crystals by X-Rays
Authors: Haworth F. E.
Published: February 2005

An apparatus has been developed in which orientations of single crystals, and the crystals in polycrystalline materials, can be studied with x-rays by rotating the specimen and moving a photographic film at the same time. The apparatus combines the best features of both the Weissenberg goniometer and that of Dawson by having the x-ray beam incident along the axis of a cylindrical film and thus recording a Debye-Scherrer circle instead of a layer line. The motion of the film and rotation of the specimen may be continuous or in steps. For motion in steps an automatic mechanism is used which exposes the film for a length of time controlled by an electric clock, and then moves the film and rotates the specimen an amount controlled by a revolution counter geared to the motor. When the cylindrical film is flattened the Debye-Scherrer circles become straight lines and a transparent net with rectangular coordinates is used to measure the angles. The data are then easily plotted in stereographic projection.
A High Efficiency Ion Source
Authors: Finkelstein A. Theodore
Published: February 2005

An ion source has been built in which the ionization efficiency of the electrons is increased without making the gas pressure excessive. This is accomplished by making the electrons oscillate through the region occupied by the gas with energies corresponding to the maximum ionization probability. The electronic space charge is used to withdraw the ion beam and hold the beam together. Hydrogen ion beams of 150 milliamperes have been obtained.
Concave Spherical Crystals of Barium-Copper-Stearate for Use in Long Wave-Length X-Ray Spectrometers
Authors: Andrews C. Luther
Published: February 2005

To perform the double function of diffracting and focusing a monochromatic beam of x-rays, multiple monomolecular layers of barium-copper-stearate were deposited upon an accurately ground concave spherical surface of glass. With a spherical crystal of radius of 218 cm, grating space of about 50.5A, preliminary photographs of the Al Kα,β region, component lines not resolved, were obtained in 30 minutes at 3 kv and 15 ma. It is believed that the intensity and resolving power from such a spherical grating are adequate for measurements with an ionization chamber of absorption coefficients at wave-lengths above 8A.
The Construction and Cooling of Large Vapor Traps
Authors: Northrup D. L. , Van Atta C. M. , Van Atta L. C.
Published: February 2005

A description is given of a simple and efficient baffle system which results in a vapor trap of high conductance for permanent gas. Two methods for maintaining the temperature of the trap in the range −50° to −80°C are described, one designed for intermittent and one for continuous operation. Measured conductances and over-all performance characteristics are given.
Notes on the Wettability of Highly Polished Metal Surfaces by Graphite Hydrosols
Authors: Szymanowitz Raymond , Porter Bernard H.
Published: February 2005

Investigation shows that a straight line relationship exists between the concentration of aqueous colloidal graphite and the minimum temperature at which it will wet unclean, highly polished surfaces of metal. Surfaces cleaned with metallographic powder and water are wetted by this type of dispersion at room temperature.
An Ionization Gauge Circuit
Authors: Bowie R. M.
Published: February 2005

Recently an article has appeared describing a new style ionization gauge. The ionization gauge circuit which is here described was designed for use with it and combines the advantages of high sensitivity, stability, and ruggedness required for industrial use. These advantages are achieved through the use of a balanced amplifier, negative feedback and gas tube voltage regulation.
An Electrical Integrator for ``Action Currents''
Authors: Freeman G. L. , Hoffman E. L.
Published: February 2005

An apparatus is described for integrating bioelectric potentials over various time intervals. This is accomplished by recording the number of times a gas-filled tube discharges a condenser which stores the rectified potentials.
A Multi-Channel Delay Unit
Authors: Marshall Wade H. , Talbot Samuel A.
Published: February 2005

Details are given for the construction of a time delay circuit of particular value for physiological laboratories using oscillographs for studying action potentials of the nervous system. It permits timing separate events at any interval in a cycle of operation determined by a master oscillator. The operation of the circuit depends on the grid extinction of a thyratron operating at low current.
Suitability of Materials for Photoelastic Investigations
Authors: Carleton R. B.
Published: February 2005

Glass, celluloid, cellulose acetate, hard and soft rubber and seven synthetic resins have been tested to determine their suitability for photoelastic investigations. The stress-strain relations, photoelastic coefficients and annealing temperatures have been measured. It is concluded that the synthetic resins Phenolite, Bakelite, and L'Orca are among the most satisfactory materials for photoelastic purposes.
A Direct-Reading, Two-Crystal X-Ray Spectrometer
Authors: Richtmyer F. K. , Barnes S. W.
Published: February 2005

A two-crystal x-ray spectrometer is described in which wave-lengths are read directly to 0.01 X.U. from the drum of a precision micrometer screw. Methods of initial adjustment are given in brief outline and as sample results there are shown the close lines Lγ2 and Lγ6 of Au(79); and the ``foot'' of Lα1 of the same element, with the accompanying satellites, the intensity of which is found to be 0.060 of that of Lα1.
Gear Ratios for Converting Civil into Sidereal Time
Authors: Flanigan A. E.
Published: February 2005

Simple ratios are computed which very closely approximate the ratio of the length of the civil second to that of the sidereal second, and which define gear trains for converting civil into sidereal time.
A Combined Recording Microphotometer, Densitometer and Comparator
Authors: Leighton Philip A. , Smith Sinclair , Henson Fred C.
Published: February 2005

An instrument which may be used as a registering microphotometer, a direct reading densitometer and a comparator has been constructed. It utilizes a radiometer as the light-sensitive device. Records are taken on 4 by 10 inch photographic plates, direct readings on a 50 cm scale, and intervals are read by means of a 10 inch comparator screw.
An Automatically Regulated Precision High Voltage Source
Authors: Schmitt Otto H. A.
Published: February 2005

It is frequently desirable to generate very steady high voltage direct current from low voltage alternating current obtained from a source subject to violent fluctuation. An instrument is described which will maintain output voltage constant to less than one percent so long as the supply voltage remains in the range between 95 and 165 volts. The variation of output voltage with changes in applied load is 0.1 percent per milliampere. The pure direct current output may be varied easily and reproducibly between 100 and 2200 volts.
Apparatus for Making Permeability-Tension Tests
Authors: Kelsall G. A. , Williams H. J.
Published: February 2005

A device is described for making permeability-tension tests on a ferromagnetic material in the form of a tape bent into a triangle. This form has the advantage over the usual straight one in that it forms a closed magnetic circuit to which tension can be easily applied. The magnetic measurements at low magnetizing forces are made by means of the Kelsall permeameter which obviates the necessity of winding a large number of turns of wire around the specimen. The magnetic measurements at high magnetizing forces are made in the customary manner with a ballistic galvanometer. The method is illustrated by tests on perminvar specimens.
Erratum: Design and Construction of an Electromagnet for Investigation of the Magnetic Properties of Atoms and Molecules
Authors: Shaw E. J.
Published: February 2005

In an article under the above title in The Review of Scientific Instruments, Volume 2, page 611, October, 1931, the unit of field strength used throughout was lines per square inch, not gauss as originally reported.
Simply Constructed Ultraviolet Monochromators for Large Area Illumination
Authors: Harrison George R.
Published: February 2005

Several types of large ultraviolet monochromatic illuminator are described, in which water or other transparent liquid is used as the dispersing medium. The most readily made consists merely of a spherical concave mirror immersed in a basin of distilled water at an angle of about 30° from the horizontal; this acts as a crude prism somewhat on the principle of the Féry quartz prism, and gives monochromatic though distorted images of a high power horizontal mercury arc used as a source. By placing an exit slit of suitable shape in the focal plane these images can be isolated one at a time, giving surprisingly pure monochromatic radiation. Such an instrument of large size can be constructed at small expense and should be useful for many types of biophysical and photochemical work. A somewhat more expensive but more distortion-free instrument can be made by using a plane mirror under water with one or two large lenses of fused quartz. The horizontal position of the input face of the water prism greatly reduces convection currents, and renders large sheets of expensive optical material unnecessary. Instruments of both types with aluminum, chromium and platinum-coated glass mirrors over eight inches in diameter have been constructed and found to operate satisfactorily. Typical spectrum photographs taken with one of the concave mirror instruments show the degree of spectrum resolution obtained.
A Refracting Interferometer for Examining Modes of Vibration in Quartz Plates
Authors: Osterberg Harold
Published: February 2005

A more sensitive method for observing longitudinal modes in vibrating piezoelectric plates consists in measuring the changes in the optical path presented by these plates to a beam of light. This is simply and conveniently accomplished by placing the transparent piezoelectric plate in one arm of a Michelson interferometer so that one of the interfering beams passes through the plate. Where a Michelson interferometer is not available, this may be accomplished in the case of a thin plate by means of the thick-film fringes formed by reflecting a beam of light from the two major surfaces of the plate. Changes in the optical path are dominated by the changes in the index of refraction of the vibrating plate. The variations of the index of refraction are markedly greater for the extraordinary ray of a light beam propagated along the Y-axis of a Y-cut quartz plate in which the compressional wave trains are propagated along the X-axis. Preliminary observations regarding the variation of the index of refraction in other crystal cuts are also presented. A brief summary is given of the longitudinal modes which have been observed in plates of quartz and tourmaline.
The Maintenance of an Independent Reed
Authors: Jones Arthur Taber
Published: February 2005

During the vibration of a free reed the flow of the maintaining wind is more rapid on the low pressure side of the tongue, and consequently the reduction of pressure on that side is the greater. The inertia of the air causes the resulting pressure difference to have a component in phase with the velocity of the tongue, thus making maintenance possible. A similar explanation is given for the maintenance of Rayleigh's ``tuning fork siren.''
The Measurement of Small Alternating Voltages at Audiofrequencies
Authors: Johnson E. A. , Neitzert C.
Published: February 2005

The origin of noise in vacuum tube amplifiers is discussed. An amplifier is described which can be used for the measurement of low voltages. A type 38 tube operated below ionizing voltages of the gas in the tube is found to have a low noise level. 10−8 volt can be measured in the audiofrequency range.
Pendulum Magnetometer for Crystal Ferromagnetism
Authors: McKeehan L. W.
Published: February 2005

The quinquefilar pendulum magnetometer of Weiss and Foëx, hitherto used only for substances of small and constant susceptibility (paramagnetic or diamagnetic) has been modified so as to be useful for small ferromagnetic specimens. For these it possesses several advantages over previous magnetometric and ballistic methods. A precise method for cutting small spheroidal specimens for the new magnetometer is described.
Piezoelectric Stabilization of High Frequencies
Authors: Osterberg Harold , Cookson John W.
Published: February 2005

It is shown that moderately thick plates of both quartz and tourmaline may be successfully employed for crystal stabilization in the frequency range from 5 to 65 megacycles/sec. Specimens which were tested by a beat method exhibited a degree of stability far within that required of commercial broadcast stations. A higher degree of stability was obtained from this thicker type of plate than was obtained from a thin plate which had been ground elsewhere. The applicability of thicker plates was foreseen from the observations that at higher frequency the modes of vibrations of plates of either quartz or tourmaline are not the longitudinal or shear thickness modes, but are rather those in which the longitudinal, flexural, or torsional wave trains are propagated in a more complicated manner throughout the body of the plate. Several of these modes are briefly described. Contrary to the conclusions drawn by Straubel, these experiments indicate that tourmaline does not possess any important advantages over quartz in the stabilization of high frequencies. Most of the plates could be caused to stabilize at several widely separated frequencies. It is shown that the resonance frequencies of quartz plates are mechanically reproducible even at 60 megacycles/sec.
Rapid Calibration and Correction of Comparator Screws and the Photographic Production of Scales
Authors: Harrison George R.
Published: February 2005

The automatic recording and computing comparator previously described has been adapted to the production of uniform and nonuniform scales. A photographic plate is clamped to the covered comparator carriage, where it is exposed to diminished images of a slit illuminated by an argon lamp which is made to flash periodically under control of the wave-length dial of the comparator. A new automatic comparator with 22-inch travel has been constructed, and the periodic errors of its screw have been reduced to less than 1 micron in amplitude by means of a new type of compensator operated by a three-dimensional rotating cam. Scales up to 20 inches long have been produced photographically in ten minutes with this instrument, those with lines 0.01 mm wide and 2 mm long spaced at 0.1 mm intervals being found convenient for screw calibration. With such a scale the recording attachment will determine the correction curve for a screw in a few minutes. The correction cam can readily be shaped to offset the error found, and fairly cheap screws can thus be made to serve for precise measurements. A satisfactory method of mounting comparator screws on ball bearings has been devised, and this feature, together with the use of a half-nut and ball-bearing rollers under the comparator carriage, reduces to one-third the torque required to operate the comparator, thus increasing its life, ease of operation, and precision.
The Design and Operation of a Large Cyclotron
Authors: Henderson Malcolm C. , White Milton G.
Published: February 2005

A large cyclotron is described with particular reference to magnet design, ``ion-source'' characteristics, radiofrequency requirements, optimum shape of the magnetic field, and the distribution in range of the high energy alpha-particle beam. Increasing the ``ion-source'' electron current above 400 ma was found to lower the efficiency of production of high speed ions. Investigation of the radiofrequency power losses showed that the anodes of the oscillators absorbed 35 percent of the total power, while the tank coil across the ``dees'' and the ``dees'' themselves took, respectively, 30 percent and 21 percent. The optimum arrangement of iron shims used for magnetic field correction was such that the average field at the middle of the pole was decidedly higher than at the edge.
Apparatus for Raman Spectroscopy at Low Temperatures
Authors: Glockler Geo. , Renfrew M. M.
Published: February 2005

An apparatus is described which permits the study of Raman spectra in the temperature range from 0 to −180°C. Its horizontal position avoids the use of a prism needed with vertical arrangements and it is easily placed into the present arrangement of light sources used in this laboratory.
Errors of the Dial Gauge as an Instrument for Measuring Amplitudes of Vibration
Authors: Weiss Herbert K.
Published: February 2005

When used for measuring amplitudes of vibration, the dial gauge was found to have two major errors, one occurring at low frequencies, the other appearing at high frequencies. The low frequency error is caused by the weakness of the hairspring which takes up backlash in the mechanism. When the critical frequency, at which the inertia of the parts overcomes the hairspring torque is exceeded, a constant error equal to the backlash appears in the gauge reading.

The high frequency error is produced by jumping of the gauge finger. By suitable installation of the gauge the jumping can be made audible to indicate the approach to the upper limit of accuracy. As the error is small for a safe range beyond this point, the audible indication provides a convenient warning.

The high frequency error is postponed by using a stronger gauge spring, and by increasing the initial compression in the spring.
Characteristics of a Split-Anode Magnetron Oscillator as a Function of Slot Angle
Authors: Rosen Leo
Published: February 2005

One of the design considerations in the split-anode magnetron is the slot angle, i.e., the angle subtended by the slot at the anode axis. The results of an experimental determination of the effect of the slot angle on the power output and efficiency of a negative-resistance magnetron oscillator operating with a constant anode current are given in this paper. It was found that the curve of power output vs. slot angle has a broad maximum between fifteen and thirty degrees.
A Differential Hot Wire Gaseous Flow Meter
Authors: Golay Marcel J. E.
Published: February 2005

A gaseous flow meter of the hot wire type with a linear response may be obtained by causing the gaseous flow to effect a transfer of heat between two adjacent heated grids.
A Triode Vacuum Tube Scale-of-Two Circuit
Authors: Lifschutz Harold , Lawson J. L.
Published: February 2005

A vacuum tube scale-of-two is described using triodes. Accurate high speed tests of the resolution time showed this to be 6.5×10−6 seconds. New methods of interpolation are also presented.
The Use of Intensifying Screens in X-Ray Diffraction Work
Authors: Gamertsfelder Carl , Gingrich Newell S.
Published: February 2005

In an attempt to reduce exposure times for monochromatic x-ray diffraction patterns of liquids, a Fluorazure intensifying screen has been used, and several tests of the applicability of this method to intensity measurements have been made. The intensifying factor for Mo Kα radiation varied from 1 for very low intensities or very short exposures, to 13.3 for intermediate intensities, and for Cu Kα radiation, it varied from 1 to 4. It appears impractical to use this screen when true intensity measurements are necessary. However, by using two ordinary x-ray films in contact, the exposure time, with Mo radiation, may be reduced to nearly one-half, and true intensity measurements may be made. With a new type of double emulsion film, true intensities are recorded and exposure times are reduced by a factor of 2.5 for Mo radiation.
A Circuit for the Rapid Extinction of the Arc in a Thyratron
Authors: Pickering W. H.
Published: February 2005

A new circuit is described which has applications for operating high speed electric counters by gaseous triodes. No auxiliary contacts are necessary, and the circuit resets itself in a period which is so short that most counters will operate near their maximum speed. The circuit thus has the advantage that it utilizes the trigger action of the gas tube to operate with a very short initiating impulse, and yet does not involve any auxiliary relays or contacts to open the arc circuit after the count has been registered.
Circuits Producing Sharp Electrical Impulses Free from Curvature and Their Use in Oscillograph Work
Authors: Morgan J. C.
Published: February 2005

A device is described for producing very sharply peaked electrical impulses devoid of the curvature at the base so characteristic of condenser discharges and peaked wave forms. The sharp impulse is applied to the grid of a greatly over-biased vacuum tube, thus only the peak of the impulse is represented by the plate current output. The advantages of such peaks in oscillograph and stroboscope work are outlined. They enable a single oscillograph element to record at least three independent quantities. The paper concludes with a note on irregularities in some frequency sources.
A High Temperature Vacuum Furnace for Spectroscopic Work
Authors: More Kenneth R.
Published: February 2005

A high temperature vacuum furnace suitable for spectroscopic investigations is described. A coil of tungsten wire is used as the heating element. Thermal insulation is provided by the use of insulating bricks. Temperatures of the order of 2000°C are attained with a power consumption of 2.5 kw.
A Simple Magnetic Apparatus for Phase Transformation Studies of Ferrous Alloys
Authors: Buehl R. , Wulff J.
Published: February 2005

A simple apparatus is described for the determination of phases and the investigation of sluggish phase transformations in ferromagnetic alloys by means of magnetic measurements made at elevated temperatures. The force exerted on a small sample is measured when it is suspended in a furnace held between the poles of an electromagnet which produce a magnetic field of uniform gradient. A few measurements on stainless steel are included.
Note on the Method of Least Squares and the Thermoelectric Power of Rhodium
Authors: Wensel H. T. , Tuckerman L. B.
Published: February 2005

The paper by Booth and Dixon ``A Discontinuity in the Thermoelectric Power of Rhodium'' is critically reviewed. The care necessary in the application of the method of least squares to physical data is discussed with references to articles giving detailed treatments. The method of least squares is then applied to Booth and Dixon's data. It is shown that: 1. The conclusions drawn by Booth and Dixon are invalid because based upon an invalid use of the method of least squares. 2. Their data are inadequate to prove the existence of a discontinuity. 3. No discontinuity of the order of magnitude reported by Booth and Dixon exists in the thermoelectric power of rhodium in the neighborhood of 1100°C. 4. No valid evidence has been adduced for a change in structure of rhodium in the neighborhood of 1100°C. In fact evidence is to the contrary. 5. Other reported ``irregularities'' of the behavior of rhodium in the neighborhood of 1100°C can reasonably be ascribed to the formation and decomposition of a surface film of rhodium oxide.