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The Astrophysical journal . shown in column 5a; each figure of this column denotes the meanof three settings on the center of the spectral line: column 56 givesthe mean of these two measures. The significance of the othercolumns is as follows: The first gives the temperature during theexposure; the second, the length of the strip of film used; the third,the displacement of the grooves for one interval of calibration; thefourth, the interval of calibration at which the measures were made; ABSOLUTE WAVE-LENGTH FROM GRATINGS 247 column 6a gives the largest difference of distance between the marka
The Astrophysical journal . shown in column 5a; each figure of this column denotes the meanof three settings on the center of the spectral line: column 56 givesthe mean of these two measures. The significance of the othercolumns is as follows: The first gives the temperature during theexposure; the second, the length of the strip of film used; the third,the displacement of the grooves for one interval of calibration; thefourth, the interval of calibration at which the measures were made; ABSOLUTE WAVE-LENGTH FROM GRATINGS 247 column 6a gives the largest difference of distance between the markand the diffraction pattern within one section,which is converted into seconds of arc in columnb, while c contains the corresponding difference ofthe constants of the grating. The accompanying Figure 3 is a copy of thesection with the mark at the right and spectral lineat the left; but unfortunately the copies do notsatisfactorily represent the originals. EVALUATION OF THE DISTANCE OF 60 The Entire Grating, January 17, 1906. Fig. 3 MarkRight Edge Spectral Line Distancefrom Markto Center of Line Difference Right Edge Left Edge Center II—I I 11=1+60 2 .0812 .081 7-9368-752 | The difference between the mark and the mean diffraction patternamounts to mm on the him. A displacement of the spectralimage on the film of mm corresponds to a rotation of the gradu-ated circle of 60. MEASUREMENT OF A SECTION I I 2 3 4 5. Distance of Mark at Right Edge from Center of Line in mm GreatestDifference a b a b a b c mm 2o?93 I23 4 6-544 4926-578 228 5 266 B 00 6 260 vOCO 2o?95 7 6-338 34° 6-339 t~~ H I5-I 8 8 260 n II 9 290 0 28 fc> 10 3°9 II 11 6-353 361 6-357 vo °< 12 350 6-356 1 vO 13 6-354 358 6-356 IN O 14 268 15 217 16i7 218 248 ERNST GIESING The following six
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectspectru, bookyear1895