,proceedings of the ,american ,academy of ,arts and ,sciences4 ,,vol4 #fa4 ,,no4 #aj--;,,july1 #aibf4 ,,on ,,the ,,distribution ,,of ,,intensity ,,in ,,stellar ,,absorption ,,lines ,,by ,,cecilia ,h4 ,,payne ,,and ,,harlow ,,shapley ,,on ,,the ,,distribution ,,of ,,intensity ,,in ,,stellar ,,absorption ,,lines#a ,footnote #a3 ,the cost of publication of this research has been met with the help of a grant from the ,rumford ,fund4 ,,by ,,cecilia ,h4 ,,payne#b ,,and ,,harlow ,,shapley ,footnote #b3 ,national ,research ,fellow4 #a4 ,it is unnecessary to emphasize the significance of the form of absorption lines in the study of problems of atomic structure and the physical constitution of stellar atmospheres4 ,there has been an abundance of theoretical work on line contour1 but a remarkable scarcity of quantitative observation4 ,the present preliminary study is aimed to meet1 in part1 the need for measurements on the broad and strong lines in the spectra of stars of various types4 ,in general the investigation has been based on objective prism spectra1 analyzed with a photographically recording microphotometer4 ,the ease with which a photometric scale can be set up on these plates1 available throughout the whole length of the spectrum1 and essentially independent of the variability of plates and development1 is a decided factor in favor of using objective prism spectra4 ,other advantages include the efficiency of the objective prism spectrograph and its simple operation4 ,the possible disadvantage of lack of purity is not important1 at least in the case of the lines discussed in this communication2 the extent to which scattered light affects the true contours of the absorption lines is considered below4 ,that the results from slit spectrographs are in essential agreement with these slitless spectrograms is shown in ,figure #a1 where microphotometer tracings of spectra from the two sources are shown4 ,through the courtesy of ,professor ,w4 ,j4 ,hussey and ,professor ,r4 ,h4 ,curtiss1 of ,ann ,arbor1 some excellent spectrograms made with the single prism spectroscope at the ,detroit ,observatory have been sent to ,harvard for this comparison4 ,the dispersion is practically the same on the ,michigan and ,harvard plates4 ,the microphotometer records were made under identical conditions for the two sets of spectra1 though the presence of comparison lines on the ,michigan plates and the narrowness of the spectra made their analysis more difficult4 ,illustration3 ,figure #a4--,microphotometer tracings made from the spectra of four stars4 ,the names of the stars1 and the sources of the analyzed spectra1 are as follows3 7#a7 ,canis ,majoris 7,sirius71 ,harvard objective prism spectrum1 7#b7 ,lyrae 7,vega71 slit spectrogram1 ,detroit ,observatory1 7#c7 ,aquilae1 slit spectrogram1 ,detroit ,observatory1 7#d7 ,pegasi1 slit spectrogram1 ,detroit ,observatory4 ,the violet ends of the spectra are to the left4 #b4 ,the work on the ,harvard spectrograms has been carried out by the method that was described in the preliminary report 7,h4,b4 #hje1 #aibd74 ,the plates were all made with the sixteen-inch refractor1 using two prisms and a special set of apertures4 ,the different apertures provide relative objective areas of #af1 #h1 #d1 #b1 and #a1 respectively4 ,the apertures are rectangular1 and the successive reducing strips are placed perpendicular to the refracting edge of the prism4 ,it is assumed in the discussion that the amounts of light admitted by the apertures are in the same ratio as their areas4 ,a standard procedure has been adopted in securing the spectrograms4 ,a series of spectra with the several apertures was obtained upon each plate4 ,focus1 clock rate1 and exposure time were kept constant over any one series4 ,in general the apertures were used in the order #af1 #h1 #d1 #b1 #af4 ,aperture #a was omitted in nearly every case1 and for a few stars other apertures were also omitted1 or found to be useless owing to faintness of the image4 ,omission of apertures is indicated by notes to ,table ,i4 ,,table ,i ,,list ,,of ,,plates ,,used ,plate ,star ,spectral ,apertures ,remarks ,number ,class ,,mc #bjgij ,lyrae ,a#ja1 #af;a1 #h1 #d1 #b ,ap4 #b not used #bjgig ,bootis ,k#ja1 #af;a1 #h1 #d1 #b1 ,ap4 #a and #b not #af;b used #bjhjj ,aquilae ,a#ea1 #af;a1 #h1 #d1 #b1 ,ap4 #a and #b not #af;b used #bafdj ,cygni c,a#baf;a1 #h1 #d1 #b1 #af;b #bafde ,cassiopeiae ,a#eaf;a1 #h1 #d1 #b1 #af;b #bafdf ,cassiopeiae ,k#jaf;a1 #d1 #b1 #af;b ,ap4 #af;b not used #bagba ,aurigae ,g#jaf;a1 #h1 #d1 #b1 #af;b #bagbb ,canis ,majoris c,f#haf;a1 #h1 #d1 #b1 #af;b,ap4 #af;b not used #baghh ,orionis c,b#haf;a1 #h1 #d1 #b1 #af;b,ap4 #af;b not used #baghi ,orionis ,b#jaf;a1 #h1 #d1 #b1 #af;b,ap4 #af;b not used #bahjb ,canis ,majoris ,a#jh1 #af1 #d1 #b ,the apertured spectra were examined1 and any that showed irregularities were rejected4 ,in cases of interference by clouds1 whether or not the spectra were visibly impaired1 the plates were not measured4 ,spectra which appeared from experience to be too strong or too weak for satisfactory analysis were also rejected4 #c4 ,the present report deals with the spectra of the eleven stars enumerated in ,table ,i4 ,successive columns contain the plate number1 the name of the star1 its spectral class1 the apertures employed1 and remarks4 ,in addition to the plates enumerated in ,table ,i1 the following focus plates were obtained4 ,plate ,star ,apertures ,remarks #bafdh ,canis ,majoris#af1 #d1 #d1 #d1 #d1 #d1 #d1 #d1,various focus settings #d1 #d1 #af #bahjc ,canis ,majoris#af1 #af1 #d1 #b1 #h1 #h1 #h1 #h1 #h1 #af #d4 ,all the plates have been analyzed by means of the ,moll thermoelectric microphotometer of ,harvard ,observatory1#c which furnishes a photographic record of the plate density4 ,the adjustments of this instrument were made with several ends in view4 ,the analyzing beam of light was kept as narrow as possible1 so that no integrating effect should enter into the final result4 ,at the same time it was desired that the total galvanometer deflection--the quantity on which the measures depend--should be of reasonable size2 otherwise the errors of measurement would become proportionately too great4 ,some of the analyzed spectra1 especially those of fainter stars1 were so narrow that the slit admitting the analyzing beam had to be considerably shortened4 ,this cut down the total light transmitted in the same proportion1 and to keep the deflections of the galvanometer of reasonable size1 a wider slit1 and therefore a wider analyzing beam1 had to be used4 ,a compromise was worked out1 for each plate1 between a narrow analyzing beam and a reasonable galvanometer deflection4 ,footnote #c3 ,this instrument was purchased with the aid of the ,rumford ,fund of the ,american ,academy of ,arts and ,sciences and the ,bache ,fund of the ,national ,academy of ,sciences4 ,special precautions were taken to secure the greatest uniformity of conditions possible throughout the analysis of each series of spectra of any one star4 ,at first it was hoped that the whole series of plates could be analyzed under exactly uniform conditions4 ,owing to the narrowness of some of the spectra1 however1 it was necessary to introduce the modifications indicated in the preceding paragraph4 ,even if all the spectra had been analyzed under precisely the same conditions1 experience showed that direct intercomparison between different stars would have been impossible1 owing to varying amounts of fog on different plates4 ,the instrumental settings were made and recorded at the beginning of the analysis of each series of spectra1 and when possible were kept untouched throughout the process4 ,the voltage supplying the analyzing beam1 and the temperature of the room1 were recorded at the beginning and end of each analysis1 since both these factors may affect the galvanometer deflection4 ,,table ,,ii ,plate ,number ,star ,slit ,width ,slit ,length ,total mm4 mm4 ,deflection scale div4 ,,mc #bjgij ,lyr 4#be #f4j #gg #bjgig ,boo 4#aj #g4j #ce #bjhjj ,aql 4#aj #g4j #db #bafdj ,cyg 4#aj #e4e #cj #bafde ,cas 4#aj #d4j #ce #bafdf ,cas 4#dj #c4j #de #bafdh ,c,ma 4#be #d4j #fg #bagba ,aur 4#be #e4j #fb #bagbb ,c,ma 4#be #e4j #gd #baghh ,ori 4#be #f4e #ia #baghi ,ori 4#be #f4j #fi #bahjb ,c,ma 4#be #f4j #ij #bahjc ,c,ma 4#be #f4j #he ,the instrumental settings for the different plates analyzed are summarized in ,table ,,ii4 ,successive columns contain the plate number1 the name of the star1 the width in millimeters of the slit producing the analyzing beam1 and the total length of that slit4 ,the effective width of the slit producing the analyzing beam differs somewhat from the quantity recorded in the third column4 ,for the three entries 4#aj1 4#be and 4#dj1 the corresponding effective slit widths are 4#aja1 4#bfb1 and 4#che mm41 respectively4 ,the corresponding widths in millimeters of the analyzing beam are #j4jaj1 #j4jbf1 and #j4jch1 respectively1 which are approximately equivalent to 4#jb1 4#je1 and 4#jh angstroms at ,h for the dispersion used in this series of plates4 #e4 ,measurement of microphotometer tracings4--,in addition to the line representing the density of the image at different points along the spectrum1 reference marks were inserted by registering a line for 8darkness10 by interposing an opaque screen in the path of the analyzing beam1 and a line for 8clear film10 by passing the beam through the plate background close to the spectrum1 though not close enough to bring it within range of disturbing photographic effects due to the image4 ,the microphotometer tracings on paper prints were measured with respect to the reference marks4 ,lines1 representing 8darkness0 and 8clear film10 were ruled from end to end of the tracing1 and across the absorption lines a curve was drawn1 completing the curve of the neighboring continuous background4 ,for early type stars this background curve can be drawn without ambiguity2 but when the spectrum is rich in lines1 the course of the unlined continuous background is largely a matter of judgment4 ,illustration3 ,figure #b4--;,diagram of an absorption line1 as registered by the microphotometer1 showing the method of measuring the tracings4 ,the quantities n 78darkness0 to 8background curve071 m 78background curve0 to 8line071 and l 78line0 to 8clear film07 were measured at intervals of five scale divisions1 indicated by the vertical lines4 ,the quantities measured on the microphotometer tracings are best described by a diagram4 ,figure #b represents a wide absorption line1 and the various distances that were measured in analyzing such a line4 ,the measures were all made with a half-millimeter rseau scale photographed upon glass1 which was laid directly upon the tracing4 #f4 ,method of reduction4--,the spectra obtained with various apertures provide1 as was pointed out in ,harvard ,bulletin #hje1 several measures of the intensity at any point of an absorption line4 ,the intensity is compared1 in the present paper1 with the intensity that the continuous background would have at the same point if the line were not present1 which is assumed to be represented by the 8background curve0 drawn across the absorption line4 ,the method has the advantage of making a determination separately for each wave length4 ,the difficulties introduced by the varying color sensitivity of the photographic plate are thus avoided4 ,it has1 however1 the disadvantage that the measured quantity depends to some extent upon the individual judgment of the investigator in drawing the 8background curve0--a matter that is simple for ,classes ,b and ,a1 but may prove serious for second-type stars4 ,the intensity differences1 background minus line1 were determined for several points by direct measurement4 ,the distances1 n and m n for the same wave length in all the spectra of any one series1 were obtained from the microphotometer tracings1 and were separately plotted against the logarithms of the corresponding apertures4 ,smooth curves were drawn1 joining the plotted points for any one wave length1 as in ,figure #c4 ,the drawing of the curves is somewhat simplified by considering together several for the same star1 remembering that the sections lying between the same abscissae should be roughly parallel4 ,these various curves represent different sections of the familiar characteristic curve for photographic blackening1 the logarithm of the aperture being here substituted for the more usual logarithm of the intensity4 ,differences of intensity between line and background are then readily obtained by interpolating values of n on the curve connecting m n and aperture1 and similarly by interpolating values of m n on the curve connecting aperture with measured values of n4 ,each spectrum thus furnished at least one1 and sometimes two1 values for the intensity difference at any point4 ,it will be seen from ,table ,,ix that for several stars two mean values of line intensity are given1 one being the mean of all the measures1 and the other the 8selected mean40 ,the selected means are obtained by using only points from the more linear portions of the characteristic curve1 and by rejecting values derived from microphotometer tracings of exceptional total deflection4 ,illustration3 ,figure #c4--,relation between galvanometer deflection 7representing plate density7 and aperture 7representing light intensity71 from measures of the microphotometer tracings made from the apertured spectra of ,lyrae1 ,,mc #bjgij4 ,ordinates are galvanometer deflections in scale divisions1 abscissae are 7above7 apertures1 7below7 logarithms of apertures4 ,smooth curves are drawn joining the points corresponding to the same wave length1 for the three apertures represented4 ,the intensity drop from background to line is thus obtained in the form log4 intensity of background minus log4 intensity of line4 ,the change in intensity may readily be converted into stellar magnitudes by dividing the difference of the logarithms by #j4d4 #g4 ,the results embodied in the present paper differ so materially from those of some previous workers1 that it is of especial interest to examine the accuracy that may be claimed for each stage of the work1 and the weight that may be assigned to the results1 7,cf4 ,harvard ,monograph ,no4 #a1 p4 #ea74 ,three stages of the investigation should be considered separately2 the plates1 7a and b71 the microphotometer records 7c71 and the measures 7d74 a4 ,accuracy of plates4--,a qualitative test of the reliability of the spectra used is made by examining the reproduction of line detail throughout the whole series made for one star4 ,figure #d shows the microphotometer tracings for a portion of the spectrum of ,canis ,majoris1 made with apertures #af1 #h1 and #d4 ,figure #e shows a similar series of tracings made from spectra of ,persei1 taken with apertures #af1 #h1 #d1 and #b4 ,it may be seen that the reproduction of line detail is satisfactorily faithful1 although a few spurious details can be detected4 ,illustration3 ,figure #d4--,microphotometer tracings made from a portion of the ,harvard apertured objective prism spectra of ,canis ,majoris1 ,,mc #bagbb4 ,the different apertures used are indicated on the left margin4 ,a few of the more important lines are marked on the lower edge of the diagram4 ,illustration3 ,figure #e4--,microphotometer tracings made from a portion of ,harvard apertured objective prism spectra of ,persei4 ,the different apertures used are indicated on the left margin4 ,a few of the more important lines are marked on the lower edge of the diagram4 ,the best quantitative test of the reliability of the spectra used in this work is the consistency of the numerical results obtained from the different members of a series4 ,from ,table ,,ix it may be seen that the residuals very seldom exceed #j4b m41 while the majority are less than #j4je m4 ,in specific criticism of the use of the objective prism in line photometry1 it has been claimed that the intensity at the line center is affected1 and measurably increased1 by stray light1 and that such an effect is inappreciable for slit spectra4 ,the results of the present work1 which deals with lines of various depths1 widths1 and qualities1 are relevant to a discussion of the question1 so far as it concerns objective prism spectra4 ,presumably the effects of stray light must be greatest in the immediate neighborhood of the stronger portions of the spectrum1 and fall off at greater distances from the more heavily exposed parts of the plate4 ,skylight contributes mainly to plate fog1 is uniform over the spectrum and its vicinity1 and is eliminated by the use of the line representing 8clear film0 as a reference base in measuring the tracings4 ,if the effects of stray light are of importance in the immediate vicinity of the continuous spectrum1 they will presumably affect all absorption lines to some extent1 and will in particular be greatest for narrow lines4 ,the effects should also be greater for heavily exposed spectra than for the more lightly exposed spectra of the same star4 ,further1 the effects of stray light should appear not only within absorption lines1 but also alongside of the spectrum on either edge4 ,a comparison of the results for ,cassiopeiae and ,aquilae1 both stars of ,class ,a#e 7see ,table ,x7 shows that the observed line depth is not1 in this case at least1 a function of line width4 ,the lines of ,cassiopeiae are both narrower and deeper 7that is1 they show greater contrast with the background7 than those of ,aquilae4 ,the same is true of ,canis ,majoris and ,capella2 the lines of the former are both narrower and deeper4 ,the results for apertures #af1 #h1 #d1 and #b have been compared for all the stars discussed1 and the intensity differences between line and background are not appreciably smaller for the larger apertures1 which would be the case if stray light were an important factor4 ,indeed1 for ,cygni and ,orionis an opposite effect is shown4 ,illustration3 ,figure #f4--,microphotometer tracing taken across the spectra of ,sirius 7,,mc #bafdg7 made with the different apertures indicated along the upper margin4 ,to examine the distribution of light at the edges of the spectrum1 a microphotometer tracing was made by running ,,mc #bahjc 7,sirius7 through the instrument in a direction perpendicular to the length of the spectra4 ,the resulting tracing is reproduced in ,figure #f4 ,effects of stray light are not to be found1 except for the strongest spectrum4 ,evidently such effects depend on the heaviness of the exposure1 but are not simply proportional to it2 they may indicate mainly the 8creep0 of the overexposed image rather than stray incident light4 ,the point of exposure beyond which stray light begins to be a disturbing factor would have to be determined separately for each plate4 ,in no case is it likely to involve any but the strongest spectrum1 and spectra that are strong enough to exhibit the effect are for other reasons not usable4 ,such measures1 in fact1 are omitted in deriving the 8selected mean10 and it would seem that effects of stray light are thus eliminated1 while an upper limit may be assigned to their magnitude by comparing the mean derived from all the measures with the selected mean in ,table ,,ix4 ,stray light1 although certainly present to some degree1 is therefore probably not an important factor in affecting the results of line photometry with the present objective prism spectra4 ,illustration3 ,figure #g4--,microphotometer tracing taken across the spectrum of ,vega made with the single prism spectrograph of the ,detroit ,observatory4 ,figure #g represents the result of a similar test made by taking a microphotometer tracing across an excellent slit spectrogram of ,vega that was made with the spectrograph at ,ann ,arbor4 ,there are no traceable effects of stray light outside the edges of the spectrum1 but on the contrary there is a distinct drop in intensity1 which may partly be due to an ,eberhard ,effect4 ,the objective prism spectrum therefore appears to have a slight advantage in this regard1 judging from a comparison of ,figures #f and #g4 b4 ,effect of focus4--,the effect of poor focus in blurring absorption lines suggests that this factor may enter into the accuracy of the results4 ,it is not possible1 in a stellar spectrograph1 when working with flat plates1 to keep all parts of the spectrum in focus at the same time4 ,two plates of ,sirius were taken for the purpose of examining the magnitude of the effect4 ,the apertures used1 and the focus settings1 were as follows4 ,,plate ,,mc #bafdh ,spectrum #a;a #c;a #c;b #c;c #c;d #c;e #c;f #c;g #c;h #c;i #a;b ,aperture #af #h #h #h #h #h #h #h #h #h #af ,setting #ag4b #ag4b #ag4d #ag4f #ag4h #ah4j #ag4j #af4h #af4f #ag4b #ag4b ,,plate ,,mc #bahjc ,spectrum #a;a #a;b #b;e #c #d #b;c #b;d #b;b #b;a ,aperture #af #af #h #d #b #h #h #h #h ,setting #af4f #af4f #af4f #af4f #af4f #af4b #af4d #af4h #ag4j ,from ,,mc #bafdh it is possible to obtain a qualitative estimate of focus effects2 ,,mc #bahjc1 including spectra taken with all four apertures1 furnishes a quantitative estimate of the magnitude of the focus errors4 ,microphotometer tracings were made1 under uniform conditions1 of the spectra of each of the focus plates1 and measures were made at the centers of the lines only4 ,for the plate ,,mc #bafdh1 the observing record book contains the entry3 8,frost in center of prism at close40 ,apparently the frosting resulted in a gradual decrease in the intensity of successive spectra1 which is shown1 when the spectra are arranged in the order in which they were photographed1 by a gradual decrease in n1 a quantity that should remain constant for the same aperture1 since the edges of the spectrum1 the portion where focus would affect the intensity1 are not crossed by the analyzing beam of the microphotometer4 ,the progressive change in n is shown in ,table ,,iii4 ,,table ,,iii ,spectrum #c;a #c;b #c;c #c;d #c;e #c;f #c;g #c;h #c;i n at ,h #ac 7#ab7 #ac #ae #af #af #ag #ah #ag ,h #h #h #h #aa #i #aj #aa #aj #aa ,h #aa #i #aj #ab #ab #ad #ab #ac #ae ,h #af #ad #ag #ae #ah #ai #ai #ai #bj ,k #ai #ag #ai #ah #bj #bb #ba #bb #bc ,h #bg #be #bh #bi #bi #ca #ca #ca #cc ,that the change in n is progressive and not due to change of focus is shown by arranging the columns in the order of focus setting1 #c;h1 #c;g1 #c;f1 #c;i1 #c;a1 #c;b1 #c;c1 #c;d1 #c;e4 ,no regular change in n is then evident4 ,the total deflection of the galvanometer is satisfactorily constant for all the microphotometer records of the spectra on ,,mc #bafdh1 excepting #c;i1 which is rejected for a large voltage drop 7#j4b volts71 producing a reduction of four scale units in total deflection4 ,spectrum #c;i is omitted from further discussion4 ,the quantity l must be corrected for change in n1 and this may be done by adding to l a quantity equal to the increase in n1 since the observed change in n1 which should be constant1 corresponds to a shift of the whole spectrum1 tending to decrease l4 ,the change in l1 the distance from 8clear film0 to line center1 as measured on the microphotometer tracings1 with changing focus1 is shown in ,table ,,iv4 ,values of l are corrected4 ,,table ,,iv ,spectrum #c;h #c;g #c;f #c;a #c;b #c;c #c;d #c;e ,focus #af4f #af4h #ag4j #ag4b #ag4d #ag4f #ag4h #ah4j l at ,h #cc #cf #dj #dg #di #di #dh #dc ,h #cg #ch #ci #dg #dg #ej #df #dg ,h #cb #ce #ca #dj #da #de #dc #dj ,h #bd #bf #bg #cc #cc #ce #cg #ca ,k #db #dd #db #ej #ej #eb #ed #dg ,h #ab #ad #ac #ai #ah #bb #bd #bj ,the line depth is the greatest1 and the focus presumably the best1 where l is smallest4 ,it appears that spectrum #c;h is at best focus4 ,table ,v contains the values of m for different focus settings1 in the same form as ,tables ,,iii and ,,iv4 ,the quantity m requires no correction for change of n4 ,for all the spectra on this plate the ,k line appears double4 ,the last line of ,table ,v contains the distance1 in scale divisions1 between the two maxima of the ,k line on the microphotometer tracing4 ,one scale division corresponds approximately to one ,angstrom4 ,,table ,v ,spectrum #c;h #c;g #c;f #c;a #c;b #c;c #c;d #c;e ,setting #af4f #af4h #ag4j #ag4b #ag4d #ag4f #ag4h #ah4j m at ,h #af #af #ad #ac #ac #ab #i #aa ,h #ai #ah #ah #af #ae #ad #ab #ac ,h #bb #bj #bj #ai #ah #ag #ae #af ,h #bd #bb #bj #ba #bb #ba #ba #ai ,k #c #c #b #b #b #b #b #b ,h #bd #bc #bc #bd #be #bc #bi #bh ,width of ,k #d #d #e #e #g #f4e #i #i ,the data of ,table ,v1 and the changing width of the ,k line 7thus shown to be an effect of focus7 indicate #c;h as being the best focussed of the nine spectra4 ,this can also be seen visually from the plate4 ,the focus plate ,,mc #bahjc was similarly analyzed and measured4 ,no progressive weakening of the spectra is shown by this plate1 and the measures are therefore uncorrected4 ,for the same plate ,table ,,vi shows the change of l with focus setting1 in the same form as ,table ,,iv4 ,,table ,,vi ,spectrum #b;c #b;d #b;e #b;b #b;a ,setting #af4b #af4d #af4f #af4h #ag4j l at ,h #ea #eb #ea #ed #ec #ddha #gg #gh #gi #gi #ha ,h #ed #ee #ef #ee #ef ,h #dg #dh #ea #ej #ej ,h #ci #ci #db #dc #da ,k #fb #fd #fe #fe #fd ,h #bb #bf #bh #bh #bf ,h #h #aj #ab #ab #h ,h #d #e #d #f #b ,table ,,vii is in the same form as ,table ,v1 and represents the change of m with changing focus4 ,evidently ,spectrum #b;c is at best focus4 ,,table ,,vii ,spectrum #b;c #b;d #b;e #b;b #b;a ,setting #af4b #af4d #af4f #af4h #ag4j m at ,h #bb #bb #ba #bj #ai #ddha #c #c #b #b #b ,h #bd #bd #bc #bc #be ,h #bh #bg #bf #bg #bf ,h #ca #ca #cj #bh #cj ,k #f #e #e #d #d ,h #cf #cc #cd #cc #cd ,h #cb #ca #cj #cj #ca ,h #bj #ai #bj #ai #ai ,by the use of the four apertured spectra that occur on ,,mc #bahjc it is possible to evaluate the differences of intensity1 produced by the change of focus1 directly in stellar magnitudes4 ,the method used in deriving the intensities is the one employed in compiling ,table ,,ix4 ,the intensities at the centers of the lines of the various spectra are summarized in ,table ,,viii4 ,it appears that ,spectrum #b;c is at best focus for lines at either end of the spectrum1 and that the curve of best focus moves towards #b;b for intermediate lines4 ,the effect is what would have been anticipated on general grounds4 ,the magnitude of the effect is satisfactorily small1 as may be seen by comparing the differences in ,table ,,viii with the residuals in ,table ,,ix4 ,errors arising from bad focus1 while they are of appreciable size1 do not exceed the errors due to other causes4 ,if the spectra to be analyzed appear upon visual examination to be in good focus1 they will probably not give results impaired by serious focus error4 ,illustration3 ,figure #h4--,microphotometer tracings made from ,harvard objective prism spectra of ,sirius1 ,,mc #bafdh1 to illustrate the effects of focus4 ,analyses are shown of the five lines indicated on the left margin1 for the focus settings given above4 ,the best focus is at #af4h2 the short lines below the absorption minima indicate the change in line depth with changing focus4 ,the doubling of the ,k line1 and the increasing distance between the components1 is a noticeable effect of focus4 ,figure #h shows1 for ,,mc #bafdh1 the lines ,h1 ,h1 ,h1 ,h1 and ,k1 for four out of the nine focus settings4 ,the change in line depth1 and the blunting of the intensity curve1 are at once apparent4 ,,table ,,viii ,spectrum #b;c #b;d #b;e #b;b #b;a ,setting #af4b #af4d #af4f #af4h #ag4j ,h 4#ec 4#ec 4#ea 4#di 4#dg #ddha 4#ac 4#ac 4#ji 4#ji 4#ji ,h 4#fj 4#ei 4#fj 4#fj 4#fc ,h 4#fc 4#fe 4#fe 4#ff 4#fb ,h 4#fb 4#fb 4#ff 4#fb 4#fe ,k 4#ae 4#ad 4#ac 4#ab 4#aj c4 ,accuracy of microphotometer records4--,as was pointed out in ,harvard ,bulletin #hje1 the width of the analyzing beam1 which is not in any case greater than one-tenth of an ,angstrom1 is such that no smoothing effect need be considered at the line center4 ,in a few cases the same line of the same spectrum was registered twice4 ,the measures made upon the two tracings were always satisfactorily accordant4 ,illustration3 ,figure #i4--,test of the consistency of spectra taken with different apertures4 ,ordinates are distance from 8clear film0 to 8line center0 taken from microphotometer tracings of spectra of ,aquilae1 ,,mc #bjhjj4 ,abscissae are the ratio 7l m for one aperture7_/7l m for twice the aperture74 ,the fact that the points lie on a smooth curve indicates that the results are satisfactorily consistent4 ,the consistency of the results given by the tracings of several spectra of the same star1 when photographed with different apertures1 may be examined by means of the plot shown in ,figure #i4 ,ordinates are values of l m4 ,abscissas are values of the ratio 77l m7 for one aperture7_/77l m7 for twice the aperture74 ,it is evident that if the points thus derived fall on a smooth curve1 the results derived from different tracings of the same spectrum will be mutually consistent4 ,the method of interpolation described in ,section #f may therefore be used in deriving the differences of intensity between line and background4 ,if the method of ,section #f is to be successfully applied1 it is essential that the total range 78darkness0 to 8clear film07 shall be uniform for a single series of tracings4 ,in general the variations in total range do not exceed three or four scale units1 but1 for some spectra1 occasional changes of eight or ten units have occurred1 generally owing to changes of voltage or room temperature4 ,under these circumstances1 it has been thought best not to attempt to apply any correction for variations in total range1 but to reject from the 8selected mean0 readings from spectra that gave very discordant total ranges4 d4 ,accuracy of measures4 ,in comparison with the errors of the plates and of the microphotometer tracings1 the errors in the measurement of the records are of relative unimportance4 ,the chief difficulty1 as mentioned above1 is that of drawing from fiducial points the reference lines representing the continuous background and the 8clear film40 ,the error thus introduced may occasionally amount to one millimeter1 or two divisions of the scale4 ,it is sometimes difficult to decide upon the position of the center of a line1 especially when it is wide1 without a sharp maximum4 ,this may lead to large residuals for measures on the wings1 especially for such lines as ,h and ,h4 #h4 ,the results of the investigation are given in ,table ,,ix1 which contains1 in successive columns1 the name of the line1 the wave length1 expressed to the nearest ,angstrom1 the mean value of the difference of intensity1 background minus line1 expressed in stellar magnitudes1 the residuals1 the 8selected mean0 value of the same intensity difference 7see ,section #f7 and its residuals4 ,the stars are mentioned at the beginnings of their respective records1 and are arranged in order of plate number4 ,in the case of stars for which no 8selected mean0 is quoted1 all the values used for the mean conform to the criterion for 8selected mean40 ,,table ,,ix ,,differences ,,of ,,intensity1 ,,background minus ,,line ,plate and ,wave ,mean ,residuals ,selected ,residuals ,star ,length,intensity ,mean ,difference ,difference ,,mc #bjgij #dhgg 4#aaa1 #d1 #d 4#aad1 #d ,lyrae #dhgb 4#bcb1 #c1 #b 4#bcc1 #b #dhff 4#dib1 #a1 #a 4#ej #dhfa 4#ieaj1 #j1 #g1 #e 4#ie ,h #dhef 4#gcb1 #c1 #b1 #c 4#gcc1 #b #dhea 4#cee1 #e1 #b1 #c 4#chb1 #a #dhdf 4#age1 #c1 #c1 #j 4#aia1 #a1 #b #dhdj 4#jgb1 #j1 #c1 #b 4#jgj1 #c1 #b #dceh 4#aaf1 #i1 #f1 #f1 #a 4#ajh1 #g #dced 4#bcaa1 #a1 #i1 #d 4#bge1 #e #dcdi 4#deae1 #j1 #ae1 #b 4#ebg1 #h #dcde 4#hch1 #c1 #ai1 #h 4#hff1 #af1 #aa #dcdj #a4dcf1 #ai1 #f1 #c1 #a4fb ,h #c #dccf 4#ibh1 #ag1 #e1 #c 4#ibh1 #ag1 #e1 #c #dcca 4#eaai1 #d1 #aa1 #ad1 4#eej1 #ae1 #aj1 #g #aa #dcbg 4#beh1 #e1 #e1 #ae1 4#bii1 #i1 #aa1 #h #ab1 #aj #dcbb 4#adb1 #d1 #d1 #aa1 #h1 4#agg1 #g1 #h1 #e #g #daaf 4#acc1 #d1 #i1 #h 4#aib1 #c #daab 4#cbaj1 #c1 #h 4#cgb1 #c #daji 4#fjae1 #b1 #ab 4#fge1 #e #daje 4#ibag1 #ah1 #ag1 #ac1 4#ibah1 #ag #e #dajb #a4fjj1 #bb1 #ae1 #e #a4hb ,h #djih #a4aa #a4aa #djie 4#gbag1 #h1 #h 4#hjj1 #j #djia 4#cca1 #g1 #a1 #c 4#cfd1 #d #djhh 4#baf1 #a1 #d1 #i 4#bbb1 #e1 #h #djhd 4#acf1 #c1 #c1 #ab 4#aee1 #e1 #aj #cihf 4#aaa1 #a 4#aaa1 #a #cihc 4#bad1 #a1 #f1 #i1 #f 4#bca1 #h1 #g1 #d #cihj 4#deaj1 #j1 #e1 #g1 #aj 4#dhc1 #h1 #d1 #g #cigf 4#gcbf1 #g1 #ad1 #d 4#hj #cigc #a4jhf1 #e1 #c1 #b #a4ag #cigj #a4fhh1 #g #a4fj ,h #cifg #a4ag #cifd 4#gjac1 #h1 #bj 4#fb #cifj 4#efba1 #d1 #ad1 #d 4#fee1 #e #cieg 4#bhaa1 #b1 #c1 #ab 4#cbb1 #g1 #h #cied 4#acc1 #c1 #a1 #g 4#acc1 #c1 #a1 #g #cicf 4#jej1 #j 4#jej1 #j #cicc ,k 4#bca1 #c1 #c1 #g 4#bca1 #c1 #c1 #g #cicj 4#aaa1 #d1 #d1 #d1 #d 4#aaa1 #d1 #d1 #d1 #d #chii 4#eee1 #e1 #b1 #j 4#ej #chie 4#gfa1 #a1 #a1 #a 4#gg #chib #a4jcd1 #c #a4jg #chhi #a4db ,h #chhg #a4aj #a4aj #chhd 4#ghc1 #b1 #c1 #b 4#ge #chhj 4#dca1 #a1 #a1 #b 4#db #chde 4#fb #chdb 4#ge #chci 4#ge #chce 4#ge ,h #chcb 4#ge #chbi 4#be #chbf 4#af ,,mc #bjgig #dcdj 4#edb1 #a1 #a ,h ,bootis #dbbg #a4cdb1 #b1 #c ,ca #dbae 4#ejg1 #h ,sr #daja 4#gdb1 #c1 #b ,h ,,mc #bjhjj #dhgg 4#jjj1 #j 4#jjj1 #j ,aquilae #dhgb 4#abe1 #e 4#abe1 #e #dhff 4#cff1 #f 4#cj #dhfa 4#gaa1 #a 4#gj ,h #dhef 4#dee1 #e 4#dee1 #e #dhea 4#bje1 #e 4#bje1 #e #dhdf 4#aec1 #b 4#aec1 #b #dhdj 4#jig1 #h 4#jig1 #h #dcfc 4#jfa1 #a 4#jfa1 #a #dceh 4#aad1 #d 4#aad1 #d #dced 4#afd1 #d 4#afd1 #d #dcdi 4#bad1 #d 4#bad1 #d #dcde 4#ciaj1 #i 4#di #dcdj 4#haa1 #a 4#hb ,h #dccf 4#ciaj1 #i 4#di #dcca 4#bad1 #d 4#bad1 #d #dcbg 4#afd1 #d 4#afd1 #d #dcbb 4#jgj1 #j 4#jgj1 #j #dcah 4#jaa1 #a 4#jaa1 #a #daaf 4#jcd1 #c 4#jcd1 #c #daab 4#aje1 #e 4#aje1 #e #daji 4#bcg1 #h 4#bcg1 #h #daje 4#dff1 #f 4#dj #dajb 4#gaa1 #a 4#gj ,h #djih 4#eje1 #e 4#eje1 #e #djie 4#bcg1 #f 4#ag #djia 4#aje1 #e 4#aje1 #e #djhh 4#jaa1 #a 4#jaa1 #a #cihf 4#bj 4#bj #cihc 4#bej1 #j 4#be #cihj 4#cbb1 #c 4#cj #cigf 4#dcc1 #d 4#dj #cigc 4#haa1 #a 4#hb #cigj #a4ej #a4ej ,h #cifg 4#gia1 #a 4#gh #cifd 4#dhac1 #ad 4#ce #cifj 4#beab1 #ac 4#ag #cieg 4#abb1 #c 4#aj #cied 4#jb 4#jb #cidb 4#ae 4#ae #cici 4#bbb1 #c 4#bj #cicf 4#ecc1 #d 4#ej #cicc ,k 4#gic1 #b 4#hb #cicj 4#eaa1 #a 4#ej #cibg 4#jge1 #e 4#ab #cibd 4#je 4#je ,,mc #bafdj #dhff 4#jgg1 #e1 #j1 #g1 4#jgj1 #j1 #j #aj1 #j1 #j ,cygni #dhfa 4#ccb1 #d1 #c1 #a1 #c1 4#cbj1 #j ,h #a1 #b #dhef 4#ahd1 #c1 #a1 #b1 #c1 4#afa1 #a1 #a #a #dcde 4#aaa1 #a1 #a1 #a1 #a 4#ajj1 #j #dcdj 4#fca1 #b1 #af1 #d1 #ag1 4#fgb1 #c ,h #af1 #b1 #g #dccf 4#baa1 #a1 #a1 #a 4#baa1 #a #daje 4#afi1 #a1 #f1 #d1 #d1 4#aaa1 #a1 #a #f #daja 4#fcag1 #c1 #af1 #b1 #b 4#efh1 #i ,h #djih 4#cgac1 #b1 #g1 #j1 #e 4#caa1 #a #cigc 4#bee1 #e1 #e1 #j1 #e1 #j1 #g1 #b1 #e1 #j1 #e #cigj 4#gjae1 #e1 #e1 #e1 #bb1 4#ffa1 #a1 #a1 #a ,h #h1 #e1 #c1 #e1 #c #cifg 4#dfbd1 #d1 #ai1 #ad1 4#cdg1 #b1 #h #a1 #d1 #af1 #ad1 #af1 #d1 #a #cicf 4#ajbj1 #j1 #c1 #e1 4#jfa1 #a #e1 #j1 #b1 #c1 #c #cicc ,k 4#edac1 #a1 #g1 #a1 #aj 4#ebc1 #e1 #c #cicc 4#cgh1 #g1 #g1 #e1 #h1 4#cec1 #b #h1 #j1 #aj ,,mc #bafde #dhgg 4#cbae1 #ae 4#dg #dhgb 4#db 4#db ,cassiopeiae #dhff 4#gbb1 #c #dhfa #a4dig1 #g1 #bc1 #g ,h #dhef 4#gbag1 #ah 4#ij #dhea 4#cdi1 #g1 #af 4#ej #dhdf 4#aca1 #c1 #d 4#ag #dced 4#cad1 #ad1 #af1 #f1 #f1 4#caaf1 #f1 #i #i1 #i1 #d #dcdi 4#dee1 #ac1 #ab1 #g1 #e1 4#deac1 #g1 #e #e1 #bc #dcde 4#haa1 #a1 #bd1 #f1 4#gee1 #j1 #e #aa1 #af1 #ba #dcdj #a4dfd1 #i1 #d1 #i1 #af ,h #dccf 4#hdcc1 #ah1 #i1 #ad1 4#hfaf1 #af #i1 #ai #dcca 4#eebj1 #ah1 #e1 #g1 4#ejac1 #ab1 #j #e1 #e1 #c #dcbg 4#cbbj1 #ae1 #b1 #ac1 4#cbae1 #ac1 #c #c1 #j1 #ag #daab 4#cdb1 #d1 #ad1 #h1 4#cjj1 #aj1 #e1 #e #a1 #a1 #f1 #a #daji 4#edd1 #ab1 #bb1 #ba1 4#dge1 #ae1 #c1 #d1 #aa1 #ac #ah #daje 4#hhb1 #h1 #ah1 #ac1 4#gee1 #e1 #j #cd1 #ag1 #ac1 #c #dajb #a4eda1 #f1 #d1 #a1 #d ,h #djih 4#hfd1 #f1 #aa1 #bi1 4#gdf1 #a1 #a1 #g #aa1 #ai1 #bf #djie 4#ecac1 #h1 #h1 #bb1 4#dgb1 #b1 #c1 #c #c1 #c1 #ad #djia 4#ccaa1 #h1 #h1 #ag1 4#bid1 #d1 #ac1 #i1 #h1 #i #d #cigf 4#hdi1 #d1 #bi1 #g1 #ef1 #ag1 #i1 #ba 4#fhac1 #i1 #a1 #g #cigc #a4cgg1 #bc1 #cb1 #ac1 #a #a4bgbb1 #bc #cigj #b4aee1 #ae1 #e1 #aj1 ,h #ab #cicc ,k #a4dhbc1 #c1 #b1 #bb1 #b ,,mc #bafdf #dhfa 4#be 4#be ,h #dddd 4#caf1 #f 4#caf1 #f ,cassiopeiae,ti #dcdj 4#dbe1 #e 4#dbe1 #e ,h #dbbg 4#hcb1 #a 4#hcb1 #a ,ca #dbae 4#gaa1 #a 4#gaa1 #a ,sr #daja 4#efaa1 #aa 4#efaa1 #aa ,h #cigj #b4eje1 #e #b4eje1 #e ,h #cicc ,k #b4dg #b4dg ,,mc #bagba #dhfa 4#dcaf1 #aa1 #d1 #cb1 ,h #aa1 #d ,aurigae #dddd 4#bai1 #ad1 #a1 #aa1 ,ti #d1 #aa1 #a #dcdj 4#gdba1 #aa1 #a1 #g1 #i1 ,h #d1 #ab #dcbf 4#fbac1 #e1 #aj1 #ac1 #e1 ,fe #ag #dbbg 4#egcj1 #cg1 #e1 #g1 #h ,ca #dbae 4#cfad1 #aa1 #a1 #d1 #f ,sr #daja 4#egj1 #ab1 #aj1 #ac1 ,h #b1 #e1 #ag #cigf 4#ecb1 #a #cigc #a4adh1 #g #cigj #a4fbac1 #e1 #ag1 #bc1 ,h #bb #cifg #a4acag1 #af #cifd 4#fb #cici 4#hjj1 #e1 #e #cicf #a4bgaj1 #aj #cicc ,k #a4fge1 #c1 #aj1 #j1 #e #cicj #a4bgaj1 #aj #cibg 4#gfd1 #f1 #a ,,mc #bagbb #dhff 4#cbe1 #j1 #aj1 #e ,canis #dhfa 4#faa1 #d1 #d ,h ,majoris #dhef 4#bhd1 #a1 #f1 #b #dddd 4#gfd1 #d1 #f ,ti #dcde #a4abg1 #h #dcdj #a4ab ,h #dccf #a4bai1 #i #dcbf 4#ghg1 #h1 #b ,fe #dbbg 4#gjaj1 #aj ,ca #dbae 4#eaa1 #a ,sr #daje 4#caa1 #a #daja 4#hfa1 #a1 #a ,h #djih 4#baf1 #f #cigj #b4be ,h #cicc ,k #b4be ,,mc #baghh #dhfa 4#bbj1 #c1 #c1 #c1 #c1 #aj 4#bej1 #j1 #j1 #j ,h ,orionis #ddha 4#bbc1 #c1 #j1 #h1 #j1 #ab 4#bbc1 #j1 #h1 #j1 ,mg #ab #ddga 4#bad1 #d1 #a1 #i1 #a1 #aa 4#afa1 #f1 #f ,he #dcdj 4#debj1 #e1 #e1 #ae1 4#cfd1 #d1 #i ,h #e1 #ah #daja 4#dcab1 #c1 #c1 #ab1 4#djj1 #j ,h #c1 #ac #djbf 4#adc1 #a1 #b1 #h1 #b1 4#abj1 #j ,he #e #cigj 4#deaj1 #e1 #j1 #g1 #e1 4#dfd1 #a1 #f1 #f ,h #ah #cicc ,k 4#agb1 #c1 #c1 #j1 #b1 4#ahb1 #b1 #a1 #c #b #chhi 4#dcab1 #ab1 #h1 #aa1 4#eda1 #a1 #b ,h #h1 #ah ,,mc #baghi #dhfa 4#bcg1 #c1 #a1 #c 4#bcg1 #c1 #a1 ,h #c ,orionis #ddga 4#caaf1 #f1 #a1 #aa 4#bj ,he #dchg 4#bdb1 #d1 #h1 #b 4#bj ,he #dcdj 4#djab1 #h1 #b1 #e 4#ce ,h #daaf 4#age1 #b1 #e1 #b1 #c 4#agb1 #b1 #c ,he #daja 4#cge1 #e1 #c1 #b 4#cfd1 #d1 #a ,h #djig 4#age1 #b1 #b1 #b 4#aej1 #j1 #j #djbf 4#aia1 #a1 #a1 #d 4#agc1 #b ,he #cigj 4#cbh1 #b1 #e1 #aj 4#cjg1 #h ,h #chhi 4#ccb1 #ad1 #f1 #aa 4#ccb1 #ad1 #f1 ,h #aa ,,mc #bahjc #dhgg 4#abc1 #b1 #b1 #j1 #b1 4#aaa1 #a1 #a1 #j #a1 #a ,canis #dhgb 4#cjbe1 #h1 #e1 #j1 4#bec1 #j1 #e1 #e1 #aj1 #e #j ,majoris #dhff 4#efaa1 #d1 #d1 #i1 4#eec1 #c1 #aj1 #f1 #d #e #dhfa #a4jbah1 #g1 #b1 #aj 4#ifa1 #d1 #d ,h #dhef 4#fgac1 #ab1 #j1 #ac1 4#feaj1 #b1 #ae1 #ab1 #j #aj1 #ab #dhea 4#caaa1 #d1 #d1 #a1 4#bib1 #b1 #c1 #d1 #a #b1 #c #dhdf 4#aci1 #a1 #c1 #c1 #b1 4#abj1 #b1 #b1 #c1 #a1 #c #j1 #b #ddha 4#bje1 #j1 #j1 #j1 #j1 #h 4#ahb1 #b1 #b1 #b1 #f ,mg #dced 4#bhb1 #f1 #g1 #f1 #a1 4#cad1 #d1 #a #d #dcdi 4#dee1 #c1 #b1 #c1 #c1 4#deb1 #c1 #b #b #dcde 4#hjaj1 #e1 #j1 #e1 #b 4#gia1 #d1 #c #dcdj #a4chg1 #h1 #g1 #f #a4cif1 #g ,h #dccf 4#hca1 #d1 #f1 #c1 #b1 4#hbe1 #c1 #c #b #dcca 4#dcc1 #a1 #d1 #h1 #d1 4#dfa1 #a1 #a #b #dcbg 4#bgc1 #e1 #c1 #j1 #j1 #j 4#bhb1 #a1 #a #dabe 4#abaj1 #g1 #e1 #b1 4#aad1 #a1 #d #b1 #c #daba 4#bjae1 #e1 #e1 #c1 4#agb1 #b1 #d #e1 #b #daaf 4#dbae1 #g1 #aj1 #j1 4#cig1 #g1 #ac #aj1 #aj #daab 4#fjae1 #e1 #h1 #ae1 4#ebj1 #j1 #j #h1 #h #daji 4#ihag1 #af1 #d1 #f 4#ige1 #e #dajb #a4deab1 #ac1 #ag1 #ae #a4dfaf1 #af ,h #djih #a4jdba1 #i1 #b1 #ab 4#ige1 #e #djie 4#fabi1 #f1 #i1 #i1 4#eca1 #a1 #b #f #djia 4#dcad1 #c1 #af1 #d1 4#cgaj1 #e1 #ae #aa1 #i #djhh 4#bdaa1 #b1 #g1 #a1 4#bjc1 #j1 #b #d1 #b #djhd 4#abaj1 #j1 #g1 #j1 #g1 4#jhc1 #c1 #g #c #cihf 4#abg1 #j1 #ab1 #e1 #aj1 4#abj1 #ab1 #e1 #b1 #j #aj1 #b1 #j #cihc 4#beg1 #b1 #g1 #g1 #j1 #b 4#beb1 #g1 #g1 #j1 #b #cihj 4#dbae1 #b1 #aj1 #ab1 4#dbb1 #aj1 #ab1 #j1 #g #j #cigf 4#ffbb1 #b1 #e1 #j1 4#ehe1 #b1 #g1 #aj #ah #cigc 4#hfbb1 #ac1 #h 4#igc1 #b #cigj #a4dgaa1 #aa1 #ah1 #aa #a4deaa1 #bj1 #i ,h #cifg #a4ajbj1 #h1 #b1 #ae #a4jbj1 #aj1 #g #cifd 4#gjbg1 #c1 #aj1 #e1 4#fde1 #b1 #c1 #ae #g #cifj 4#dgbc1 #b1 #e1 #c1 4#dcb1 #a1 #g1 #c1 #g1 #aj #f #cieg 4#ccbd1 #j1 #f1 #j1 #h1 4#bhe1 #a1 #e1 #c1 #h #c #cied 4#bcai1 #d1 #f1 #ac1 4#afaa1 #a1 #f1 #d #aa #cicc ,k 4#ahab1 #b1 #f1 #d1 #c1 4#agc1 #e1 #e1 #b #f #chhi #a4dhg1 #i1 #ag1 #af #a4ee ,h #i4 ,table ,x contains a summary of the results1 for line centers only4 ,successive columns give the name of the star1 the spectral class1 the absolute magnitude1 and the drop in magnitudes from background to line center1 for the spectrum lines mentioned at the heads of the columns4 ,the greater line depth for absolutely brighter stars1 at least among those of the second type1 is especially to be noted4 ,,table ,x ,,drop ,,in ,,intensity1 ,,from ,,background ,,to ,,line ,,center1 ,,for ,,eleven ,,stars1 ,,expressed ,,in ,,stellar ,,magnitudes ,star ,class ,m ,h ,h ,h ,h ,k #dbbg #dbae ,ori ,b#j 4#bc 4#dj 4#cg 4#cb ,ori c,b#h #e3 4#bb 4#de 4#dc 4#df 4#ag ,lyr ,a#j #j4f 4#ie #a4dc #a4fj #a4fh 4#bc ,c,ma ,a#j #a4b 4#if #a4ci #a4df #a4dg ,cyg c,a#b #d3 4#cc 4#fc 4#fc 4#gj 4#ed ,aql ,a#e #b4d 4#ga 4#ha 4#ga #a4ej 4#gi ,cas ,a#e #a4f #a4di #a4df #a4ed #b4ae #a4dh ,c,ma c,f#h #c3 4#fa #a4ab 4#hf #b4be #b4be 4#gj 4#ea ,aur ,g#j #j4j 4#dc 4#gf 4#eg #a4fb #a4fg 4#eg 4#cf ,boo ,k#j #j4c 4#ed 4#gd #a4cd 4#gj ,cas ,k#j #j4j 4#be 4#db 4#ef #b4ej #b4dg 4#hc 4#ga #aj4 ,the material contained in ,table ,x is reproduced in ,table ,,xi1 where the intensity at the line center is expressed in terms of percentage of the background intensity1 instead of in stellar magnitudes4 ,the 8background intensity10 as defined in ,section #f1 is the intensity that the background would have if the line were not present4 ,it is noteworthy that1 for the great majority of the lines1 the residual intensity at the line center is greater than #cj per cent of the background intensity4 #aa4 ,the material presented above constitutes the first systematic study of the contours of strong absorption lines4 ,in view of the preliminary nature of the work the discussion has been devoted for the most part to presentation of method4 ,extended discussion seems at present to be premature1 and only a few points need be mentioned4 ,probably the chief interest of ,table ,x lies in the result that the maximum intensity drop from background to line recorded for any of these stars is #b4ej magnitudes1 corresponding to a light loss of ninety per cent4 ,except for the supergiant c,f#h star and the ,ca absorption for ,cassiopeiae and ,h for ,cassiopeiae1 the light remaining at the center of the line is at least fifteen per cent of the background intensity4 ,on the average for all these strong absorption lines there is something like twenty-five per cent of the background light remaining at the center of the lines4 ,the significance of these residual intensities will be discussed in a later publication1 when the forms of the lines as shown by the data of ,table ,,ix will also be considered4 ,,table ,,xi ,,residual ,,intensities ,,at ,,line ,,centers1 ,,expressed ,,as ,,percentages ,,of ,,background ,,intensity ,star ,class ,h ,h ,h ,h ,k #dbbg #dbae ,ori ,b#j #ha #fi #ga #gd ,ori c,b#h #hb #ff #fg #fe #hf ,lyr ,a#j #db #bg #bc #ba #ha ,c,ma ,a#j #da #bh #bf #bf ,cyg c,a#b #gd #ef #ef #eb #fa ,aql ,a#e #ea #dg #ea #be #dh ,cas ,a#e #be #bf #bd #ad #bf ,c,ma c,f#h #eg #cf #de #ac #ac #eb #fc ,aur ,g#j #fg #ej #ei #bb #ba #ei #gb ,boo ,k#j #fa #ea #bi #eb ,cas ,k#j #gi #fh #fj #aj #aj #dg #eb ,for the wider lines1 especially those that are strong and heavily winged1 the intensities derived in this paper are probably of the right order4 ,probably1 however1 the dispersion used is too small to reproduce satisfactorily the detail at the centers of lines as narrow as those of such stars as ,cygni and ,orionis4 ,the difficulty introduced does not involve inaccuracy of plates1 microphotometer1 or process of measurement2 it is concerned solely with the fact that the spectral region examined is so narrow that1 with the dispersion used1 the grain of the plate is not fine enough to reproduce the spectral detail4 ,the same difficulty would prevent any recognition of the double reversal of the solar ,h and ,k lines1 if they were studied with the present dispersion4 ,whatever the dispersion used1 the same qualification must be made in discussing the results2 probably the dispersion would have to be greatly increased before the measured effective line depth becomes much greater for narrow line stars4 ,relative effective line depth1 derived from numerous spectra made with the same dispersion1 is still1 however1 of considerable significance4 ,it permits us to recognize differences of surface gravity1 and to form an idea of relative chromospheric depths for different classes of stars4 ,,summary #a4 ,the investigation deals with the determination of the depth and contour of prominent absorption lines in the spectra of stars of various classes4 #b4 ,the spectra used were made with the #af-;inch refractor of the ,harvard ,observatory1 using two prisms and a special set of apertures4 #c4 ,results are presented for eleven stars1 of spectral class ranging from ,b#j to ,k#j4 #d4 ,the spectra were analyzed under uniform conditions by means of the ,moll thermoelectric microphotometer4 ,the resolving power of this instrument is such that no integrating effect need be considered in discussing the results4 #e4 ,the microphotometer tracings were measured with reference to fiducial lines representing 8darkness0 and 8clear film10 and to a line1 representing the continuous background1 drawn across the absorption lines4 #f4 ,the intensity drop from continuous background to line was deduced graphically from the measures4 #g4 ,the accuracy of the results is discussed in detail4 a4 ,the reliability of the plates1 as judged from qualitative reproduction of detail1 and from the consistency of the numerical results1 is satisfactory4 ,effects of stray light are of negligible magnitude1 and in this respect slit spectra appear to have no advantage over objective prism spectra4 b4 ,effects of poor focus are measurable1 but small4 ,spectra that are in such poor focus as to cause appreciable inaccuracy would be rejected from visual inspection4 c4 ,the accuracy of the microphotometer tracings is in general satisfactory4 ,tracings showing abnormal deflections from 8darkness0 to 8clear film0 are not susceptible of correction1 and are omitted in deriving results4 d4 ,the measures upon the tracings are also of satisfactory accuracy4 #h4 ,the differences in intensity between the continuous background and various points along the line contour are tabulated for the eleven stars under discussion4 #i4 ,the general results for the intensities at the centers of lines show an interesting relation to absolute brightness2 the brighter stars have1 in general1 lines that cut more deeply into the background4 ,a result of considerable interest is that the average residual intensity in the strong wide absorption lines is more than #cj per cent of the background intensity4 ,,volume #fj4 #a4 ,,daly1 ,,reginald ,a4--,the ,geology of ,ascension ,island4 pp4 #a-hj4 #ba pls4 ,june1 #aibe4 #c4jj4 #b4 ,,barnett1 ,s4 ,j41 ,,and ,,barnett1 ,l4 ,j4 ,h4--,new ,researches on the ,magnetization of ,ferromagnetic ,substances by ,rotation and the ,nature of the ,elementary ,magnet4 pp4 #abe-baf4 ,july1 #aibe4 #a4ej4 #c4 ,,baxter1 ,g4 ,p41 ,,and ,,cooper1 ,w4 ,c41 ,,jr4--,a ,revision of the ,atomic ,weight of ,germanium4 ,,ii ,the ,analysis of ,germanium ,tetrabromide4 pp4 #bai-bcg4 ,october1 #aibe4 #j4ge4 #d4 ,,dana1 ,l4 ,i4--,the ,latent ,heat of ,vaporization of ,liquid ,oxygen-,nitrogen ,mixtures4 pp4 #bda-bfg4 ,october1 #aibe4 #j4ge4 #e4 ,,pierce1 ,,george ,w4--,piezoelectric ,crystal ,oscillators ,applied to the ,precision ,measurement of the ,velocity of ,sound in ,air and ,,co#b at ,high ,frequencies4 pp4 #bga-cjb4 ,october1 #aibe4 #j4ge4 #f4 ,,bridgman1 ,p4 ,w4--,certain ,physical ,properties of ,single ,crystals of ,tungsten1 ,antimony1 ,bismuth1 ,tellurium1 ,cadmium1 ,zinc1 and ,tin4 pp4 #cje-chc4 ,october1 #aibe4 #b4ej1 with #g and #h4 #g4 ,,bridgman1 ,p4 ,w4--,various ,physical ,properties of ,rubidium and ,caesium and the ,resistance of ,potassium ,under ,pressure4 pp4 #che-dba4 ,october1 #aibe4 #b4ej1 with #f and #h4 #h4 ,,bridgman1 ,p4 ,w4--,the ,effect of ,tension on the ,transverse and ,longitudinal ,resistance of ,metals4 pp4 #dbc-ddi4 ,october1 #aibe4 #b4ej1 with #f and #g4 #i4 ,,boschma1 ,h4--,on the ,symbiosis or ,certain ,bermuda ,coelenterates and ,zooxanthellae4 pp4 #dea-dfj4 ,october4 #aibe4 #j4ej4 #aj4 ,,kennelly1 ,a4 ,e41 ,,and ,,slepian1 ,,arthur4--,computation of the ,behavior of ,electric ,filters ,under ,load4 pp4 #dfa-dhc4 ,october1 #aibe4 #j4ge4 #aa4 ,,franklin1 ,,wm4 ,s4--,indeterminism in the ,physical ,world4 pp4 #dhe-ejb4 ,november1 #aibe4 #j4ej4 #ab4 ,,yeh1 ,,chi-,,sun4--,the ,effect of ,hydrostatic ,pressure on the ,magnetic ,permeability of ,iron1 ,cobalt1 and ,nickel4 pp4 #ejc-ece4 ,december1 #aibe4 #j4ej4 #ac4 ,,roebuck1 ,j4 ,r4--,the ,joule-,thomson ,effect in ,air4 pp4 #ecg-eif4 ,december #aibe4 #j4ge4 #ad4 ,,records ,,of ,,meetings2 ,biographical ,notices2 ,officers and ,committees2 ,list of ,fellows and ,foreign ,honorary ,members2 ,statutes and ,standing ,votes4 etc4 pp4 #eig-gaj4 ,december1 #aibe4 #j4ej4 ,,volume #fa4 #a4 ,,lewis1 ,,frederic ,t4--,a ,further ,study of the ,polyhedral ,shapes of ,cells4 pp4 #a-ce4 ,december1 #aibe4 #j4ej4 #b4 ,,heidel1 ,w4 ,a4--,the ,calendar of ,ancient ,israel4 pp4 #cg-ef4 ,december1 #aibe4 #j4ej4 #c4 ,,bridgman1 ,p4 ,w4--,the ,effect of ,pressure on the ,viscosity of ,forty-three ,pure ,liquids4 ,february1 #aibf4 pp4 #eg-ii4 #j4ge4 #d4 ,,bridgman1 ,p4 ,w4--,thermal ,conductivity and ,thermal ,e4,m4,f4 of ,single ,crystals of ,several ,non-cubic ,metals4 pp4 #aja-acd4 ,february1 #aibf4 #j4ge4 #e4 ,,slater1 ,j4 ,c4--,measurements of the ,compressibility of the ,alkali ,halides4 pp4 #ace-aej4 ,april1 #aibf4 #j4ej4 #f4 ,,palache1 ,,charles4--,contributions to ,mineralogy from the ,department of ,mineralogy and ,petrography1 ,harvard ,university4 #ab4 ,catalogue of the ,collection of ,meteorites in the ,mineralogical ,museum of ,harvard ,university4 pp4 #aea-aei4 ,may1 #aibf4 #j4be4 #g4 ,,rogers1 ,,austin ,f4--,a ,mathematical ,study of ,crystal ,symmetry4 pp4 #afa-bjc4 ,june1 #aibf4 #j4ge4 #h4 ,,brues1 ,,charles ,t4--,studies on ,ethiopian ,braconid1 with a ,catalogue of the ,african ,species4 pp4 #bje-dcf4 ,june1 #aibf4 #b4ej4 #i4 ,,davis1 ,,tenney ,l41 ,,and ,,abrams1 ,,armand ,j4 ,j4--,studies in the ,urea ,series4 pp4 #dcg-deg4 ,june1 #aibf4 #j4ej4 #aj4 ,,payne1 ,,cecilia ,h41 ,,and ,,shapley1 ,,harlow4--,on the ,distribution of ,intensity in ,stellar ,absorption ,lines1 pp4 #dei-dhf4 ,june1 #aibf4 #j4ej4 ,,publications ,,of ,,the ,,american ,,academy ,,of ,,arts ,,and ,,sciences4 ,,memoirs4 ,,old ,,series1 ,vols4 #a-d2 ,,new ,,series1 ,vols4 #a-ad4 #af volumes1 #aj each4 ,half volumes1 #e each4 ,discount to booksellers and ,libraries #be2 to ,fellows #ej1 or for whole sets #fj4 ,vol4 #ac4 #a4 ,curtiss1 ,d4 ,r4--,binary ,families in a ,triply connected ,region with ,especial ,reference to ,hypergeometric ,families4 pp4 #a-fj4 ,january1 #aijd4 #a4jj4 #b4 ,tonks1 ,o4 ,s4--,brygos3 his ,characteristics1 pp4 #fa-aai4 #b pls4 ,november1 #aijd4 #a4ej4 #c4 ,lyman4 ,t4--,the ,spectrum of ,hydrogen in the ,region of ,extremely ,short ,wave-,length1 pp4 #aba-adh4 pls4 iii-viii4 ,february1 #aijf4 #ge;c4 #d4 ,pickering1 ,w4 ,h4--,lunar and ,hawaiian ,physical ,features ,compared1 pp4 #adi-agi4 pls4 ix-xxiv4 ,november1 #aijf4 #a4aj4 #e4 ,trowbridge1 ,j4--,high ,electro-motive ,force1 pp4 #aha-bae pls4 xxv-xxvii4 ,may1 #aijg4 #ge;c4 #f4 ,thaxter4 ,r4--,contribution toward a ,monograph of the ,laboulbeniace4 ,part ,,ii4 pp4 #bag-dfi4 pls4 xxviii-lxxi4 ,june1 #aijh4 #g4jj4 ,vol4 #ad4 #a4 ,lowell1 ,percival4--,the ,origin of the ,planets1 pp4 #a-af4 pls4 i-iv4 ,june1 #aiac4 #fj;c4 #b4 ,fernald1 ,w4 ,e41 ,southard1 ,e4 ,e41 and ,taft1 ,a4 ,e4--,waverley ,researches ,in the ,pathology of the ,feeble-,minded4 7,research ,series1 ,cases ,i to ,x47 pp #ag-abh4 #bj pls4 ,may1 #aiah4 #f4jj4 #c4 ,fernald1 ,w4 ,e41 ,southard1 ,e4 ,e41 ,canavan1 ,m4 ,m41 ,raeder1 ,o4 ,j41 and ,taft1 ,a4 ,e4--,waverley ,researches ,in the ,pathology of the ,feeble-,minded4 7,research ,series1 ,cases ,,xi to ,,xx47 pp4 #abi-bjg4 #cb pls4 ,december1 #aiba4 #f4ej #d4 ,pickering1 ,edward ,c41 ,parkhurst1 ,j4 ,a41 ,aitken1 ,robert ,g41 ,curtis1 ,heber ,d41 ,mitchell1 ,s4 ,a41 ,alden1 ,harold ,l41 ,simpson1 ,t4 ,mc,n41 and ,reed1 ,f4 ,w4--,photometric ,magnitudes of ,faint ,standard ,stars1 measured visually at ,harvard1 ,yerkes1 ,lick and ,mc,cormick ,observatories1 pp4 #bji-cjg4 #i pls4 ,august1 #aibc4 #f4jj4 #e4 ,thaxter1 ,r4--,contribution towards a ,monograph of the ,laboulbeniace4 ,part ,,iii4 pp4 #cji-dbf4 #ab pls4 #f4jj4 ,vol4 #ae4 #a4 ,jeffrey1 ,e4 ,c4--,the ,origin and ,organization of ,coal4 pp4 #a-eb4 #ac pls4 ,november #aibd4 #c4jj4 #b4 ,mills1 ,hiram ,f4--,flow of ,water ,in ,pipes4 7,with a historical and personal note by ,john ,r4 ,freeman and introductory outline by ,karl ,r4 ,kennison74 pp4 #ee-bcf4 ,portrait4 #f ,figs4 ,november1 #aibd4 #g4ej #c4 ,fernald1 ,m4 ,l4--,persistence of ,plants in ,unglaciated ,areas of ,boreal ,america4 pp4 #bcg-cdb4 #gc maps4 ,june #aibe4 #e4jj4 ,,proceedings4 ,vols4 #a-fj1 #e each4 ,discount to booksellers and ,libraries #be2 to ,fellows #ej1 or for whole sets #fj4 ,the individual articles may be obtained separately4 ,a price list of recent articles is printed on the inside pages of the cover of the ,proceedings4 99 99 99 99 99 ,complete ,works of ,count ,rumford4 #d vols41 #e4jj each4 ,memoir of ,sir ,benjamin ,thompson1 ,count ,rumford1 with ,notices of his ,daughter4 ,by ,george ,e4 ,ellis4 #e4jj4 ,complete sets of the ,life and ,works of ,rumford4 #e vols41 #be4jj2 to ,fellows1 #e4jj4 ,for sale at the ,library of ,,the ,,american ,,academy ,,of ,,arts ,,and ,,sciences1 #bh ,newbury ,street1 ,boston1 ,massachusetts4 ---------------------------------------- -------------------------------- ,,transcriber',s ,,notes ,typos fixed2 non-standard spelling and dialect retained4 ,used numbers for footnotes ,enclosed italics font in underscores4 ,enclosed bold font in equals4 ,subscripts are shown using an underscore 77 with curly braces 1 as in ,h#b,o4