ON A TABLE OF STA^^DARD \YAYE LENGTHS OF TUE SPLcillAL LINES. Ml 
TADLE X. 
DESCRirTiox OF TAr.Li:. 
In the first column is the metal to which the line mcn^nrcd is siippo?r.l to l)vl<>nL^ 
Where 'a solar line 'is measured, it often hclongs fo several metals, tlioiiirh ilio \h\v<t 
ily coincident. Wlien they are nppnrcntly coincident, thc} 
<Ti on 
one 
Fe Ti. If the iron had coincided with the violet ^ide and tlio TV 
14 'J t i ' ' 
d 
side it would have been written thus: ^r>. Ih.d the iron line coin 
J > 
cided with the violet side only, and the T, not at all, it vvotild hnve brm w.ittru 
thus : n ^ 
Tl 
coknnn n-ivins the intensity in the arc is a very ron-h attempt oid) •^\ W 
M' 
O' ' O 
intensity as it appeared on the plates, without attciupting to dcfuie the Ffro,.,. ,( 
line by any fixed number. The stronger the line the larger the number. 'J ho 
: intensities in the solar spectrum are also only roughly ebiimatcd. 
• In the next column the fifteen visible standards are ph.ml together with^the A 
and another group at about 7200, which were used 
diflic 
region. Next to these, wider sets of Hues depending on these were «»e.l n, <!.<, 
strndards. so that the mean of a number of observations could be taken. 
M 
The eye ob 
The ph 
marked with letters ;>, <7, U, C, etc. 
plates, most of which have coincidences with tho bh.o-viul.l 
throuuli llic 
or ultra-violetrare marked Plate 1, Plate ^2, eta, to Plate 23, and 
whole solar spectrum from ^yave line 300-5 to 7201. 
Ti>e platL havin, the solar spoetrun. -^-:f^^:r^:f:^:^:^ZZ 
metallic spectra alone, are marked O M. 44 „, M^ 20 ^^'^^'^^^ ,„, ^,,, 
with a grating having 20,000 lines to the meh. The m K ^_^^ 
and Tr,etaUic spectra were taken at wave length 4400 m tl e . ec j 
the metallic spectra at 2900 in the third, and 2200 m the fourth. «or. al 
' The substandards are put in where reaui..d>^^ ^^^ ^^^ _^^^^^,„^^^^„, 
The small letters a, I, c, refer to the divimn^ li^ 
G means solar, and M metallic, and E reversed. 
19 
VOL. XII. 
