572 
MR. J. NORMAL LOC'KYER OX SPECTRUM-ANALYSIS 
It is most important tliat both the negative and transparency should not be var¬ 
nished, as the texture of the varnish will, when photographed, mar all fine detail. 
VI. CONCLUSION. 
In conclusion, I would remark that the accompanying map can only be regarded 
as provisional, seeing that when greater dispersion is employed, or a grating without 
the glass plate in front of it is available, much finer details will no doubt be revealed, 
and wave-lengths of all lines will be directly given. 
With regard to the detail shown, I believe that the map as nearly represents the 
actual state of the solar spectrum at the epoch as can be expected with the photo¬ 
graphic materials and dispersion at my disposal. There are some few lines which, 
when magnified, seem to show indications of being double, in some cases by a shading 
off on one side, in others by a trace of a central division. Such lines are, however, 
represented in the map as single, and the words “probably double” introduced oppo¬ 
site to them in the tables. 
I may also mention that in other cases a solar line, although single under the 
highest magnifying power, has also been suspected to be double, because in my work on 
metallic spectra the supposed components have been found to be coincident with two 
lines in the spectra of two distinct metals, which lines just graze each other without 
actually coinciding. 
The coincidence of the solar lines with those due to the vapours of the metals in 
this region I shall deal with in another paper. 
In the annexed plate I have not only given the map, as reduced from the photo¬ 
graphs in the manner described, but introduced a permanent enlargement of one of 
the photographs. It has not been possible to represent the intensities absolutely, 
on account of the varying tones of the absorption-lines themselves. The untouched 
photograph will allow of the detection of any errors of this nature. 
I must express my obligation to the authorities of the School of Military Engineering, 
Chatham, for the permission they granted to have the enlargements made, and the 
reduced copy of the map photographed, there. 
It is my duty and pleasure to record my deep obligations to my assistants, Messrs. 
Meldola, Ord, and Starling for the care, patience, and skill they have successively 
shown in carrying on the various branches of the work. My thanks are also due to 
Corporals Murray and Ewings, Ii.E., for their aid in enlarging the sketch maps and 
comparing them with the original negative. 
In the map the lines have been fined down as much as possible to show the double 
lines, and the shading near Id and K reduced to a minimum to show the finer fines in 
those regions. 
