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XII. Researches in Spectrum-Analysis in connexion with the Spectrum of the Sun .— 
No. V. 
By J. Norman Lockyer, F.R.S. 
Received April 29,—Read May 23, 1878. 
[Plate 67.] 
Contents. 
I. Introduction. 
II. Refraction Map. 
A. Instruments, &c. 
B. Method of Mapping. 
a. Construction of Interpolation Curves . 
/3. Construction of the Map. 
7 . Determination of Wave-lengths, new lines 
HI. Diffraction Map. 
A. Instruments, &c. 
B. Determination of Wave-lengths. 
C. Construction of the Map. 
IV. Importance of the Photographic Method. 
V. Photographic Process Employed. 
VI. Conclusion. 
Page, 
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571 
Tables. 
I. Table of Lines used in construction of Interpolation Curves (Refraction Map) . . . 573 
II. Table of Lines Interpolated from Curves (Refraction Map). 574 
III. Table of Wave Lengths. 575 
I. INTRODUCTION. 
It lias long been clear that the means placed at our disposal by photography for 
studying the solar spectrum enable us to construct maps of the region more 
refrangible than b on a much larger scale than those hitherto employed. 
At the same time, as our knowledge of the molecular conditions under which 
changes in spectra occur is increased, it becomes necessary to embrace more and more 
detail in the inquiry. 
Hence in former communications to the Hoyal Society I have pointed out that in 
order to increase our knowledge of the sun’s chemical constitution, and to have a 
MDCCCLXXXI. 4 D 
