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FIGURE V] 16 mm. High Intensitv White Flame Positive and 11mm. Neutral Cored Negative Rurning at Ordinary Current Densitv of ?5 Amperes and 63 Volts Direct Current, viewed from the side. FIGURE VII .White 16 mm. I{igh Intensity Flame Positive and 11 mm. Neutral Cored Negative Burning at High Intensity Condition of 150 Amperes and ?3 Volts Direct Current. \tiewed from the Side. l FIGURE VIII 16 mm. High Intensity White Flame Positive and 11 mm. Neutral Cored Negative Burning at High lntensit5r Condition of 150 Amperes and ?3 Volts Direct Current. Viewed from the Front. FIGURE XVI FIGURE XI FIGURE X ( Omitted ) l-p1,us5isn Blug 2-Ultramarine 3-Cobalt BIue {-puapls lskg 5-Cobalt Violet g-Qsfslf Qlssn f-pmslsld Qlssn g-lgrn6n Chrome 9-Cadmium YeIlow 10-Yellow Ochre 11-Orange Vermillion 12-Vermillion 1S-White 14-Black see Loyd A. Jones'paper, page B6 I I I i FIGURE XII | 4:41
flame of fairly high luminosity and similar to the flame of the ordinary White Flame Arc shown in Figure IV coming from the positive carbon. If the current density is increased to values, which previous to the development of this kind of arc were thought impracticable, a marked change takes place in the arc. The flame from the negative carbon assumes a {orce and directional power which, if the angle between the carbons is right, confines the positive luminous flame to a small space near the positive carbon. At the same time the face of the positive carbon is hollowed out, tak;ng a shape much like the inside of a cup. The action of the negative flame, pushing the positive luminescent flame back into this cup-shaped crater so compresses the positive flame that it {orms in the bottom o{ the crater what appears to be an incandescent gas ball of higher brilliance per unit area or intrinsic brilliancy than any other arc and under certain conditions this intrinsic brilliancy is higher than that of the sun itself. A side view of this so-called high intensity arc is given in Figure VII and a front view in Figure VIII. A comparison of Figure VI and Figure VII shows the change which takes place in the appearance of the arc when the current is increased. The apparent brilliance per unit area of the difierent light sources considered and the sun is given in the following table: Light Source Candle Power per SQ.MM Iligh Intensity White Flame Carbon Arc. Forced 1200 Sun at Zenith 920 High Intensity White Flame Carbon Arc as Usually Operated---------.-- 690 Positive Crater of Cored Carbon Arc on Direct Current-------- 130 Yellow Flaming Arc Stream (Similar to Pan t'O")------------ 8 The high intensity carbon arc forced or so-called super high intensity is receiving consideration at the present time {or searchlight work. Current densities are used on carbons {or this work which are 60/o higher than that used in the ordinary high intensity arc. It has been said in the literature of the high intensity Arc that the color of the light emitted from the crater and gas ball cannot be afiected. We have found, nevertheless, that it can be changed to a certain extent. The color of the emitted light probably cannot be changed from the blue-white to a red but it is possible to change it from a blue white to a white or yellow white and work is in progress on carbons in which this change will have been accomplished, These carbons, however, will probably have more application in the projdction field that in the studios themselves. It is of considerable interest to know the distribution of energy emitted by the various types of Flame Arcs in the various wave lengths or colors of the spectrum. The curves in Figure IX show the distribution of the energy from the White Flame and Panchromatic "O" Carbon Arcs, In these curves fl 'l (6 iE z2 ; ) FIG.D( @Es6Ydgmr&-M Cffi +- PACHFOMAft 'O' G&Ng la W Mgs VERTI4 APC @W EEIECrcF t5@E 5&ERS ,DFr@ffi U@tutu / \- 7 / the eneigy in any part of the spectrum is plotted so that each square on the curve of the original plot is equal to 1x107 watts of energy per square millimeter on a surface a distance of one meter from the arc. The Agnstrom units used as abscissae, indicating the different wave lengths o{ light are l/1'0 oi the millimicron units which are sometimes used. The light or energy shown on the curves below 4000 units is invisible to the eye and the energy shown on the curves below 3400, as has been indicated by Mr. Rayton at this convention, is of no value in photography with the ordinary lens systems because wave lengths of light below about 3400 Angstrom units will not pass through ordinary glass. The light or energy above 7000 Angstrom units is the infra red or heat rays and cannot be seen by the eye and does not afiect the photographic material ordinarily used in the studio. It can be seen that the White Flame Arc has a fairly uniform distribution of energy above 3900 Angstrom units but at 3800 to 4000 units is somewhat higher than at any other point. This peak is characteristic of all carbon arcs but can be influenced by the current, voltage and material in the core. The curves of the new Panchromatic "O" Carbon Arc as can be seen from the Figure has a lower peak at this point than the white flame arc but a higher peak or concentration of energy at 5500 to 6500 Angstrom units, which is the yellow, orange and red part of the spectrum. This latter peak is what gives this Panchromatic "O" Carbon Arc its characteristic color and makes it very useful as a light source with panchromatic film since it tends to overcome the low sensitivity of panchromatic film in the red, yellow and orange as compared with its high sensitivity in the blue and violet. Since the same current and voltage was used in obtaining the values for these curves in Figure IX, it is readily seen that the change in the distribution of energy is caused entirely by the materials in the core. The manner in which the energy distribution of the light source influences the photography of colors is illustrated by Figures X, XI, and XII. Figure i4sl
Page 1: ACADEMY RE,PORTS lNo. 1l INCAI{T}ES
Page 4 and 5: Academy of Copyrighted By the Motio
Page 6 and 7: INTRODUCTORY STATEMENT The followin
Page 8 and 9: ment supplied {or carrying out this
Page 10 and 11: was discussed at some length with t
Page 12 and 13: lamp or globe replacements, as comp
Page 14 and 15: COMMENTS ON LABOR COSTS Although no
Page 16 and 17: amount to be moved. Undoubtedly, th
Page 18 and 19: g "Heat is too great and leak light
Page 20 and 21: "In regard to value, the tests have
Page 22 and 23: ROOSEVELT The following'scenes were
Page 24 and 25: QursrroN: What color filters were u
Page 26 and 27: morning. But now, through the balan
Page 28 and 29: portant fields for experiment in co
Page 30 and 31: make-up is a great help in keeping
Page 32 and 33: is best defined by stating the rela
Page 34 and 35: photometric curves, they serve to s
Page 36 and 37: divided into three equal portions r
Page 38 and 39: We can now apply the various fundam
Page 40 and 41: of energy radiated by tungsten in t
Page 42 and 43: high temperatures and it is quite h
Page 44 and 45: to reduce this radiation is to use
Page 48 and 49: X is the reproduction of a color ch
Page 50 and 51: Carbon Arc and Incandescents in the
Page 52 and 53: Since there is a steady diminution
Page 54 and 55: to refer to a test which was recent
Page 56 and 57: the plane perpendicular to the line
Page 58 and 59: lenses used in motion picture photo
Page 60 and 61: ':t FINAL SESSION OF THE ACADEMY I
Page 62 and 63: tubes have been practically discard
Page 64 and 65: lended together to more efficiently
Page 66 and 67: ought together all the various Bran
Page 68 and 69: matographers and the Society of Mot
Page 70 and 71: T Y P E o F N C .at N D E C E N T E
Page 72 and 73: T Y P E F N C o N D E c E N T E a U
Page 74 and 75: o T Y P E F N C n N DESC (NOT FOR S
Page 76 and 77: TYPES OF INCANDESCE.NT EQUIPMENT Me
Page 78 and 79: QUALITY OF ILLUMINATION EXPERIMENTA
Page 80 and 81: BIBLIOGRAPHY "Effective Application
Page 82: PRODUCERS E. II. Allen E. M. Asher

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