96 PROFESSOR PIAZZI SMYTH ON 
destroyed the gift of rarefied gas in the spectroscope to look hard, solid, ard 
sharp? You have rather increased it, if your electric light keeps up well, and if 
your prisms are good, your spectroscope’s slit perfect, and your objectives 
faultless ; for as you now survey the whole angular extent with the telescope 
of the spectroscopic apparatus, all appearance of dull smooth undefined haze is 
gone; and almost everywhere, from the red on one side, right round the 
whole horizon until you come to the violet,—you see only luminous lines sharp 
and hard ; lines that will suffer no more splitting up under prism power; no 
more dulling of their light by dispersion, though they may by the absorption of 
many more glass prisms. They have arrived then at their ultimate condition, 
and behold how exquisite they are; how beautifully ordered in their ranks, 
how varied in their groups, how perfect in structure, contrasted in intensity, 
and indexed ready to one’s hand by colour. It is almost endless work 
merely to admire them; quite endless for poor, finite, human nature to try 
to measure them all. , 
The only thing to compare with it would be a ring of the whole Heavens 
at once, on a bright and starry night when the firmament is shining with the 
countless glories of distant moving suns, the so-called fixed stars, And each 
of these innumerable bright lines in the electric-lighted spectrum of the 
cyanogen tube is as fixed, practically for ever, in spectral distance, the one from 
another, as each of those starry orbs ; so that a practical observer who should 
employ thereon throughout half his life all the angular forces of a mural circle, 
would by such observations be donating posterity with an heirloom of absolute 
knowledge of the most important and lasting kind. 
But even then the spectrum task is only at its beginning; for on each occasion 
that the spectroscopist changes a tube of one, for any other, gas, instantly the 
whole angular round is peopled with a new set of spectral but eternal lines ; 
each of which knows its own place, flies into it in less than the twinkling of an 
eye, and a new spectroscopic universe in lines of light is the result. Who would 
not, if he could, be an observer, to some extent, of such phenomena; and, as 
for the cui bono use of it, if “the trains of thought” it leads the intelligent 
mind to, be not enough reward for ever,—then scientific history shows that _ 
the discovery of such a mine of accuracy in measure of place, and perfection in 
number, will be sure to have its practical applications in human education, and 
many industrial pursuits as well, before long, 
In this present paper permit me to begin simply as follows— 
PRACTICAL COMMENCEMENT DESCRIBED, 
This consisted, in my case, in the examination of the 20 tubes alluded to, 
with merely a single and simple prism power: in the spectroscope, combined 
