158 PROFESSOR A. S. HERSCHEL ON 
tlutings are really independent from each other in their derivations, and that the array of lines 
on their two slopes are not fellow-representatives of a common arithmetical progression, The 
general want of conformity among the line-intervals of the second slope may perhaps arise, 
accordingly, from the superposition upon each other of the two unconformable line systems of 
the two interfering slopes; and a character which seems to be essential to the linelets of the 
second slope independently of every influence of conflicting impurities in the tube upon their 
comparatively slender strengths, possibly receives from a conjecture of this kind a satisfactory 
interpretation. That ruled and lined bands like those of olefiant-gas and other “carbon ”- 
spectra possess, it would seem, insular characters in a spectrum, the minuteness of whose 
description, as revealed in the imposing tables of green gas-flame, and green tube-carbon bands 
drawn up by Professor P1AzzI SMYTH, surpasses comprehension, and almost registration, will I 
believe be granted from a close inspection of his observations and 1eductions. But if the 
inherent complexity of these shaded bands’ internal structures proves to be so prodigious as the 
application of extraordinary dispersion shows, it is scarcely to be expected that among the close 
array of these ruled wedge-like luminosities crowded thickly into the nitrogen procession, order 
should reign among their leading, or frontier lines. Systems well studied on a larger scale 
appear here to be repeated, and innumerably multiplied in miniature. A comprehensive and 
far-reaching theory of banded and fluted spectra will therefore probably be required to include 
and account intelligibly for all the singular changes of orderly succession that the nitrogen 
flutings present when the positions of their leading edges, or in other words the space-intervals 
from spur, or terrace-edge to terrace-edge of the long serration, are further brought into com- 
parison with each other. 
In the extreme red, numerous groups were seen with the powerful end-on illumination, 
preceding any of those pictured and mapped by Piiicker and Hrrrorrr, and by Ancstrém and 
THALEN. A few measures among these revealed a far-off line, star-like in its brightness, which 
proved to be a triple, and even quadruple line when brought into the middle of the field of 
view. It had already been measured and recorded accurately with low dispersion by Professor 
Prazzi SMyrtH as a Nitrogen-line ; and the result of the new measures of this part of the Nitrogen 
spectrum was to connect it, as shown in the Table, with a well-observed series of extreme-red 
nitrogen groups, of which it formed the first visible commencement. Its two least refrangible 
lines agree in their spectral positions with the two spurs or leading edges of a double-toothed 
serration, while its two more refrangible ones lie upon the fading flank of the second tooth’s 
slope, at nearly the same equal distances asunder. In both Cyanogen and Nitrogen they were 
equally sharp and bright, like weak hydrogen or lithium lines, quite free from the haze and 
haziness connected with the corresponding linelets in other portions of the spectrum. 
But if end-on vision has revealed an outwork so substantial and remote as this of the dark 
red portion of the nitrogen procession, what may perhaps be gathered from the announcement 
of a “fine line” at the head of the list, in a view of the spectrum of air in an end-on vacuum 
tube, contained in a record of that spectrum as measured with a prism of ordinary dispersion, 
communicated by Professor P1Azzi Smytu last year in his Paper on “ End-on Illumination in 
Private Spectroscopy” to the Royal Scottish Society of Arts, the spectral position of which is 
1150 inch-units lower in its wave-number than this frontier line of nitrogen, and which is 
actually but little more refrangible than the dark-red Potassium-line itself? * The interval to 
* Ina careful search for low-temperature lines in an oxygen gas vacuum tube, Professor Prazz1 SMyrTH has met 
with an extreme-red line at W. No. 32,600 (circa), which may perhaps be identical with that above noticed as mapped 
in an ‘‘air-spectrum” at about W. No. 32,670, The latter line, in that case may perhaps be an oxygen-line, and not 
a nitrogen-line as here supposed. 
