444 - Proceedings. 
means of that instrument in the hands of skilful observers. In a paper published in the 
Nineteenth Century for February, Mr. Norman Lockyer presents us with a portion of the 
results of the last ten years’ work in this branch of science. From the one hundred 
thousand observations recorded by him, he deduces the wonderful fact, that the fixed 
stars may be roughly divided into four classes, distinguished by their (presumed) difference 
in temperature. He shows that the brightest and hottest of the stars have a spectrum, 
** marvellously simple," indicating in the main only two substances, hydrogen and calcium, 
with faint traces of magnesium, and perhaps of sodium. Stars of the second-class are 
neither so bright nor, it is believed, so hot. In this class our own sun is included, though 
even = — is spoken of by Mr. Lockyer as so great as to be ‘ beyond all 
Stars of this class give a spectrum in which the indications of hydrogen are 
eaim dicen the evidences of the existence of calcium are increased in intensity, 
as are also the indications of sodium and magnesium; while the simple character of the 
spectrum of the first-class has been replaced by a combination of lines of “ terrible com- 
_ plexity.” In speaking of the other two classes of suns, I will quote Mr. Lockyer's own 
words:—:* The complexity which we meet with in passing from the first-class to the 
second, is one brought about by the addition of the lines protaal by bodies of chemical 
substances of moderate atomic weight. The addition ity observed when we pass 
from the second to the third, is brought about by the addition of sake due in the main to 
bodies of higher atomic weight, and—this is a point of the highest importance—at the 
third stage,” that is, in the third-class of suns, “the hydrogen, which existed in such 
abundance in stars of the first-class, has now entirely disappeared. In the last class of 
stars to which I have referred, the fourth, the lines have given place to fluted bands, at 
the same time that the light and colour of the stars indicate that we have almost reached 
the state of extinction.” Mr. Lockyer puts the same facts in simpler form, thus— 
The hottest stars show lines of..H + Ca + Mg 
2. The sun H + Ca + Mg + Na + Fe 
3. The cooler stars Mg + Na + Fe + Bi + Hg 
4. The coolest; fluted bands of metals and metalloids. 
In the cooler stars the elements are found in a state of greater combination, while in 
the hottest they are dissociated by the int heat, so that the older (and therefore cooler) 
a star has become, the less of free hydrogen will appear. On the earth the process of 
cooling has reached the stage in which hydrogen is no longer found in a free state. All 
that is here stated from Mr. Lockyer’s paper, though extremely interesting in the connec- 
tion in which I have introduced it, occurs in the original as part of the reasoning which 
leads to the conclusion that nad of the Alaina vhi hare hino wn perdam as 
elementary are probably 
tures which exist in the hotter kinds of stars. Thus a general law is indicated er 
may apes expressed in these words:— The lowering of temperature in a mass of matter is 
accompanied by a gradually increasing complexity of chemical forms : and, of course, the 
converse holds good that the higher the temperatnre the more completely will the elements 
which form the chemical compounds be dissociated. 
Before passing from this subject, it will not be out of place to express the opinion 
that we have here one of the greatest discoveries of these days, and one which opens out 
a new field of investigation to which it is not easy to assign a limit. 
me mente a an me i 
plication of science to the 
comfort and convenience of man, but time will not permit mo: 
