Galvanometer Readings Research Articles

THROUGH THE INFRARED WITH LOGBOOK AND LANTERN SLIDES - A HISTORY OF INFRARED ASTRONOMY FROM 1868 TO 1960

Only nine years after Kirchoff published his radiation laws and eleven years before Stefan published the fourth power of absolute-temperature law, the fourth Earl of Rosse made the first infrared measurements of any astronomical body other than the Sun. He observed the Moon with a thermopile and the three-foot reflector at Birr Castle in 1868 (Rosse 1869, 1870, 1873). I begin this history of infrared astronomy with his work because he introduced two techniques, one of which was used for 80 years and the other, in modified form, is still used today. Filters that isolated infrared wave bands and were opaque to visible light did not exist, and so he conceived of using a plate of glass as a filter. By differencing the galvanometer readings with and without the glass and suitably correcting the glass readings for reflection losses, he measured the infrared flux from the Moon. This technique I will call subtractive filtering, and it was used until 1950. His first measurements were made with a single thermopile, and he discovered immediately that the galvanometer deflections were strongly influenced by changing telescope temperatures and air temperatures. He then conceived of using two identical thermopiles, one connected in opposition to the other, both side by side in the focal plane ofthe telescope. Only one thermopile was exposed to the Moon; the other saw only sky. This compensation technique is replaced today by the ac equivalent of chopping between the object and the sky. Lord Rosse compared his lunar deflections with those from blackened cans containing water of different temperatures, and he made extinction measurements at different elevations ofthe Moon. From these he derived a temperature ofthe full Moon of 400°-500° F, presumably by linear extrapolation ofthe water-can deflections. His same measurements can now be interpreted with Stefan's law and they do give the correct temperature ofthe Moon (Sin ton 1958). He measured the lunation curve of the Moon, and he also observed a total eclipse. He noted that the infrared deflections from the Moon during the eclipse were closely proportional to the visible light, and he deduced that the Moon's surface cooled extremely rapidly. His apparatus was not sufficiently sensitive to

A differential method of determining the thermal properties of materials

A method for determining the thermal properties of materials is described, which enables one to distinguish small differences in the thermal properties of two specimens. Only two galvanometer readings need to be taken. The method belongs to the category of “electrical measurements of nonelectrical quantities.”

Cytophotometric Data on Fluorochromed Cervical Cells<xref ref-type="fn" rid="FN1">2</xref>

A simplified fluorophotometric device for measuring the light emission of the whole-cell area of single isolated cells is described. Ehrlich ascites carcinoma cells stained with the basic fluorochrome acridine orange were used for a model experiment. The sensitivity of the used photomultiplier 1P21 for the green-yellow emitted by the nuclear area was about 4 times greater than that for the metachromatic red of the cytoplasmic and nucleolar ribonucleic acid. Galvanometer readings over concentric cell areas of varying diameters showed that nuclear emission was mainly responsible for the total recorded fluorescence intensity. Photometric data obtained on single fluorochromed cervical cells gave mean emission values approximately 2 times higher for abnormal than for corresponding normal cells. Emission values of abnormal cells were distinctly above the level of a dividing line at 36.2 emission units and were well separated from normal cells. The differential staining of nucleus and cytoplasm by a basic fluorochrome with well-delineated nucleo-cytoplasmic boundaries is of advantage for detection of cellular atypia by visual observation. In addition, cytophotometric data can yield valuable evidence in closer identification and separation of degrees of cellular abnormalities, especially where cytologic classification and tissue findings are not conclusive.

An electrochemical method of recording the pattern of oxygen metabolism in the tissues in vivo

The author suggests a very simple method for the measurement of oxygen metabolism in animal tissues, which is based on a simplified polarograph system and electrodes with internal galvanic effect. Electrodes, used for the above purpose, consist of a copper cathode with amalgamated active surface, a needle from ordinary carbon steel acting as an anode. The cathode is made from lacquered copper winding PEL, 0.5–0.9 mm in diameter by amalgamating the cone-shaped tip with mercury. The above pair of electrodes, connected through a galvanometer, is inserted into tissues and oxygen metabolism is assessed through galvanometer readings.

The Distribution of Light Reaching the Ground Vegetation in a Tropical Rain Forest

A survey of light reaching the undergrowth of a Tropical Rain forest in Bukit Timah Nature Reserve, Singapore, was made on two days during March 1957. A description of the site and vegetation, and an account of the observations made under sunny conditions, has already been published (Whitmore & Wong 1959). The apparatus, using a reflecting paper plate viewed from above by a photocell, and the method of survey and of evaluation of the data followed that used in Rain forest in Nigeria by Evans (1956). Two sample plots of 5 x 25 ft (1 5 x 7*6 m) were marked out, each being divided into five equal, square sub-plots. Owing to the hilly nature of the ground these two sample plots were not completely identical, but gave a representative idea of the variation likely to be encountered in the mature forest in this area. Twenty-five observations were made, one in each corner and one in the middle of each square sub-plot, thus surveying 30 % of the area of the whole plot, and these were repeated at approximately quarter-hour intervals. Records were made (i) of the galvanometer reading; (ii) of whether the sun was obscured by cloud (c), or by haze (h), or was shining brightly (s) and in the last instance (iii) of the proportion of the reflecting paper plate occupied by sunflecks. The category 'hazy' was used to describe those occasions when the sun's disc was obscured by a veil of mist or light wispy cloud so thin that vague bright patches appeared on the forest floor. This state of affairs, negligible at the time of Evans's observations in Nigeria, was recorded in Singapore on 12 % of occasions. The climate of Singapore also differs from that of southern Nigeria (during the dry season) in having very frequently cloud and rain during the afternoon and occasionally at mid-day-predominantly sunny afternoons being a rarity. Thus, while we have an opportunity to compare conditions in the two tropical forests while the sun is shining, by considering also the cloudy periods we are enabled to tackle a number of questions which have not so far been considered in previous analyses:

Simple technique for recording variations of a few centimetres in galvanometer reading

Simple technique for recording variations of a few centimetres in galvanometer reading

Direct graphical representation of helium katharometer indicator and other galvanometer readings.

Direct graphical representation of helium katharometer indicator and other galvanometer readings.

A slide rule for calculating blackening curve separations

A slide rule has been devised for simplifying the operations in calculating blackening curve separations, obtained from galvanometer readings, without plotting density curves or using tables. In its present form the slide rule is suitable only for spectrograms where the background correction is negligible ; under such conditions a considerable saving of time and effort is claimed.

Use of fluorescein in testing the union of parabiotic rats.

Summary1. Two methods, one using free fluorescein and the other protein bound fluorescein, were employed to test the capillary anastomosis between rats united in parabiosis. Free fluorescein was demonstrable by galvanometer readings on the abdominal skin of the recipient in fewer than half of the experiments. Protein bound fluorescein, on the other hand, was uniformly detected in the heart blood of both donor and recipient over a period ranging from 4 1/2 to 24 1/2 hours. Precipitation tests were also positive in demonstrating the presence of protein bound fluorescein in heart blood. 2. Parabionts tested by either method showed no adverse effects from the treatment and were in good condition for subsequent investigations. By testing a group of parabionts with protein bound fluorescein one could determine the adequacy of the parabiotic union prior to further experimentation.

A direct-reading microdensitometer

The instrument gives galvanometer readings which are directly proportional to the density of the photographic plate under examination and are independent of fluctuations of the light source. This result is achieved by making appropriate use of a logarithmic triode amplifier. High gain is attained by measuring the intensities of the transmitted and the direct beams of light by an electron-multiplier phototube, any fatigue effects being avoided by employing the same phototube for both beams.

Application of the Seidel transformation to the determination of intensity ratio by blackening curve separation

Methods for shortening the work required to obtain blackening curve separations at a low constant density are discussed. By employing Seidel densities, blackening curves are obtained sufficiently straight for accurate separations to be derived by plotting two points on each curve and joining these points by a straight line, thus reducing the number of microphotometer readings required and eliminating curve fitting. A simple method of plotting Seidel densities directly from galvanometer readings by means of a suitably graduated scale is described and this, in conjunction with a special scale for measuring line to background separations, shortens the method and renders the use of mathematical tables unnecessary, even when background correction is required.

Fluid Saturation in Porous Media by X-Ray Technique

Abstract This paper describes the application of x-ray theory to design procedures inconnection with fluid saturation determinations during fluid flow experimentswith porous media. A reliable and rapid method for calibrating the x-rayapparatus is described. Extension of the method to fluid saturationdeterminations in three-fluid systems is described. Introduction In research on oil production problems a method is required which will givequickly the quantity of each component of a fluid flow system present at anycross-section of a porous medium. The sample of porous medium under investigation is usually referred to as acore. The ratio of the volume of one component to the total fluid volume isdefined as the saturation of the porous medium by that component. This ratio isgenerally given as per cent saturation. Some means of measuring saturation which have received considerationinclude: electrical conductivity of the fluids; emissions from radioactivetracers dissolved in the fluids; the radioactivity of silver caused byreflection of neutrons from hydrogen atoms in the fluids, the attenuation of amicrowave beam, the diminution and phase shift of ultrasonic wave trains, andthe reduction in intensity of x-ray beams in passing through the fluids. X-rays have already been used with some success. Since every material has adifferent power to absorb x-rays, the reduction in intensity of an x-ray beamas it passes through a core depends on the fluids present. The strength of theemergent beam can be found by converting its energy into a measurable form suchas heat or ionic current, or by its effect on a photographic plate orfluorescent screen.. The beam strengths could be interpreted as quantities ofknown fluids in the core if, previously, these beam strengths had beenidentified with a known combination of the same fluids. With some fluidcombinations it might be desirable to dissolve powerful x-ray absorbingmaterials in one or more of the fluids, to increase the differences in the beamstrengths for various fluid saturations. Boyer, Morgan and Muskat have described a method of measuring two componentfluid saturation. One component was air or water; the other, mineral seal oilin which was dissolved 25 per cent by weight of iodobenzene to increase itsabsorbing power. The x-ray source was a tungsten target tube operated at 43 kvpotential. The beam emerging from the core was measured as ionic currentflowing across an air-filled ionization chamber by means of an amplifyingcircuit and galvanometer. Another portion of the beam from the x-ray tube waspassed through a metal plate and measured in another ionization chamber. Thisportion, called the monitor beam, was used as an indication of the performanceof the x-ray tube. The galvanometer readings were calibrated against air-oilcore saturations, gravimetrically determined. The method was apparentlyestablished by experimental means. T.P. 3169

Microclimate close to the ground.

RECENT communications1,2 have directed attention to the importance to the biologist of the peculiar microclimate on the ground and among ground vegetation. A thin hot layer of air covers the surface of bare earth in sunshine, and among vegetation it is lifted to a height which depends upon the height and density of the vegetation. Measurement of the temperature of this air is difficult: the temperatureprofile is steep and is likely to be disturbed by the ventilation of an aspiration thermometer. When using an aspiration thermocouple over bare earth, I have found that the galvanometer reading rises initially to a high value and then falls, suggesting that hot air is being withdrawn and replaced by colder.

Infrared radiation from the region of the galactic center.

view Abstract Citations (3) References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Infrared radiation from the region of the galactic center. Stebbins, Joel ; Whitford, A. E. Abstract During the summers of 1945 and 1946 a search was made at Mount Wilson for evidence in infrared light of a nucleus or bright region at the center of the galaxy. Using the 6o-inch reflector with a photocell and filter giving effective sensitivity at 10,300 A, the procedure was to keep the telescope stationary and allow the sky to drift past a focal diaphragm of 8 6 diameter for 15 or 20 minutes of time. With galvanometer readings at intervals of 39 seconds, any object would be measured once in passing across the field. Similar sweeps with a red filter with sensitivity at 7190 A served to identify foreground stars or star clouds by their color. In `945 the area ~0 each side of the galactic equator from longitudes 3250 to 3290 was covered with sweeps at intervals of 6', allowing for some overlap, while in 1946 the area was extended in both latitude and longitude with sample sweeps at intervals of o?~. A persistent series of maxima appeared near the equator of the Lund tables with pole at 12h40m, +280(1900). This elongated bulge is roughly outlined by a figure some 80 long and 3?5 wide with center at longitude 326?5. The ratio pf the red and infrared intensities give a color excess near 2 magnitudes, international, compared with about 0.5 magnitude for the great cloud in Sagittarius, some four degrees away, which Baade has shown is undoubtedly the outer region of the bulge about the galactic center. The infrared surface intensity of the central region turns out to be magnitude 19 per square second of arc, referred to the infrared brightness of an Ao star at the zenith, but the photographic brightness would be something like magnitude 24.5 per square second, more than 2.5 mag. or 10 times fainter than the darkest piece of blank sky in the neighborhood. Hence, to photograph the bulge with blue-sensitive plates would mean the detection of an addition of 10 per cent to the blank sky brightness superimposed also upon the star clouds in the foreground. The conversion of our red minus infra measures into international color excess of 2 mag. and thence to total photographic absorption of 8 mag. is rather doubtful, but it is evident that we are dealing with a very red region about the center. Although a concentrated nucleus has not been found, it is believed that the central region of the galaxy has been outlined, because of its position, its form, and especially its color. Washburn Observatory, Madison, Wis. Publication: The Astronomical Journal Pub Date: 1947 DOI: 10.1086/106022 Bibcode: 1947AJ.....52R.130S full text sources ADS |

Observations on the Ascorbic Acid Content of Evaporated Milk

The ascorbic acid content of evaporated milk has been investigated by Meulemans and de Haas (9), who concluded that the canned product contains as much vitamin C as does p r e p a r e d fresh milk. These workers apparently used a direct titration procedure with 2,6-dichlorobenzenoneindophenol and obtained data ranging from 20 to 30 rag. per liter of ascorbic acid in evaporated milk reconstituted to a fluid basis. Henry, Houston, Kon and Osborne (3), using the precipitation technique of Kon and Watson (8), titrated milk serum with the indophenol dye and found losses of about 30 per cent in the total ascorbic acid content of evaporated milk due to manufacture, with a subsequent gradual loss in storage. Appreciable quantities of dehydroascorbic acid were noted upon reduction of the milk serum with hydrogen sulfide, scrubbing with nitrogen and subsequent titration. Woessner, Elvehjem and Schuette (13) found only insignificant amounts of dehydroascorbic acid in evaporated milk using a photoelectric method and extrapolating galvanometer readings to zero time, which procedure they found corrected errors due to spurious reducing substances resulting from the effect of hydrogen sulfide on milk ingredients other than dehydroascorbic acid. These workers state that the metallic nature of the manufacturing equipment is not related to the ascorbic acid content of evaporate(~ milk nor are the use of stabilizing salts, the degree of preheating or geographical considerations. Kon and Henry (7) noted a loss of 43 per cent in the ascorbic acid content of fresh fluid milk as a result of sterilizing at a temperature of 230 ° F., whereas Josephson and Doan (5) showed that moderately high temperatures (170 ° F. to boiling) cause a stabilization of the ascorbic acid of milk as a result of heat produced, sulfhydryl, reducing substances derived from certain milk proteins.

Sensitivity and Resolution of Moving Coil Galvanometers. I

The volt and ampere sensitivity of a moving coil galvanometer is treated in terms of the electrical circuit, the galvanometer design, and the time used for taking observation. Only cases where the current is constant are discussed; ballistic use is not treated. The term ``resolution of galvanometer readings'' is suggested to describe the experimentally determined change in potential difference or current that can be measured with a stated probable error in a stated measuring time under actual working conditions. The use of a galvanometer as a deflecting, partial-deflecting and null instrument is discussed.

The Determination of Blood Plasma Carotene in the Bovine using a Photoelectric Colorimeter

Summary 1. A simple phase separation of carotene from bovine plasma has been outlined. 2. When petroleum ether is used as the solvent the boiling point and temperature of extraction are important factors in the amount of carotene extracted. 3. When petroleum ether with a boiling point of 73–76° C. was used and the extraction carried out at 10–12° C. the epiphase gave true carotene values. 4. When the phase separation method is used, the relationship of the amount of carotene in the epiphase to the total amount present in the sample should be established. 5. The temperature at time of pipetting into the absorption cell under ordinary laboratory conditions had no measurable effect on the galvanometer readings. 6. The use of 15 ml. of a 95 per cent ethyl alcohol for precipitation of the proteins from 10 ml. of plasma was found to be advantageous. 7. Shaking the tubes for two to three minute periods gave more consistent results than shaking for one minute. 8. The addition of 0.5 ml. of alcohol to destroy emulsions had no effect on the determination. 9. The method was shown to give consistent results from day to day. 10. Plasma stored at 2.0° C. showed no loss of carotene over a period of three weeks. 11. The use of the phase separation method in conjunction with the photoelectric colorimeter offers a simple and rapid procedure for the determination of carotene in bovine blood plasma.

Glass Electrode with Galvanometer Reading

Glass Electrode with Galvanometer Reading

A vertical‐intensity magnetometer

Magnetic observations, and in particular those necessary for the control of magnetograph records, at stations in high magnetic latitudes have been greatly handicapped, because of unfavorable magnetic conditions as well as temperature conditions at such stations, for lack of a suitable instrument to determine rapidly and with precision the vertical intensity of the Earth's magnetic field. The establishment of the Godhavn Magnetic Observatory in Greenland, where the magnetic inclination is about 82°, led the author to consider electrical methods of determining the magnetic vertical‐intensity of the Earth's field. An experimental apparatus was used during a trip to Greenland in 1925 to select a site for the Observatory, and as a result of these experiments a new type of vertical‐intensity magnetometer was developed and was sent in August 1926, after trial at the Rude Skov and Potsdam observatories, to the Godhavn Observatory for use there regularly.The essential part of the new instrument is a precise standard for mutual inductance, that is, an inductor with two sets of windings, and very strongly built, By rotaiing the standard 180° on a horizontal axis the vertical intensity of the Earth's magnetic field gives rise to electromotive forces in the windings. One winding is connected with a ballistic galvanometer which, through the arrangement described below, measures the induced effect; the sensitivity of the galvanometer is such that rotating the inductor 180° would cause a deflection quite beyond the scale‐limit of the galvanometer, for example, at Rude Skov for a scale‐distance of 2 meters, a deflection of 10 meters. This arrangement, a sort of zero‐method, by which the deflection of the galvanometer never exceeds a few centimeters even for highest sensitivity of the apparatus, utilizes an accurately determined electric current which, during the turning of the inductor, may be made or broken in the second winding. The making or breaking in this current through the second winding induces an electromotive force in the winding connected with the galvanometer, and the connections are such that the electromotive force induced by the variation of the “compensating current” is opposite to the electromotive force induced by the vertical component of the Earth's magnetic field during a turn of the inductor. Thus, the resulting deflection of the galvanometer corresponds to the difference of the two induced electromotive forces. By again turning the coil and using some other compensating current, a second galvanometer reading is obtained. By means of two such readings the strength of a compensating current, which should give just the zero‐deflection of the galvanometer, is readily computed.

A Study of Pfund’s Pressure Gage

Pfund’s combination of the McLeod and Pirani pressure gages was studied with a number of gases. The calibration curves of pressure against galvanometer reading were found to be straight lines and, except for hydrogen, nearly interchangeable for all the gases used. By using a galvanometer of high sensitivity and introducing a compensating filament, the sensitivity of the gage was increased until a change in pressure of 1.5×10−9 mm of mercury would cause a change in deflection of 1 cm on the galvanometer scale.Brief comments are made on the release of carbon monoxide and air from coconut charcoal and on the adsorption of air at low pressure by silica gel.