140 REPORT—1868. 
On the Results of Spectrum Analysis as applied to the Heavenly Bodies; 
a Discourse delivered before the British Association at Nottingham, 
on August 24, 1866. By Witi1am Hvueains, F.R.S., Hon. Sec. to 
the Royal Astronomical Society. 
(Abstract*.) 
[Plates III. 1V.] 
Tue speaker commenced with a few preliminary remarks on the importance 
to Astronomy of the analysis of light by the prism. The researches of 
Kirchhoff have placed in the hands of the astronomer a method of analysis 
which is specially suitable for the examination of the heavenly bodies. So 
unexpected and important are the results of the application of spectrum 
analysis to the objects in the heavens, that this method of observation may 
be said to have created a new and distinct branch of astronomical science. 
Physical Astronomy, the imperishable and ever-growing monument to the 
memory of Newton, may be described as the extension of terrestrial dyna- 
mics to the heavens. It seeks to explain the movements of the celestial 
bodies on the supposition of the universality of an attractive force similar to 
that which exists upon the earth. 
The new branch of astronomical science which spectrum analysis may be 
said to have founded, has for its object to extend the laws of terrestrial 
physics to the other phenomena of the heavenly bodies, and it rests upon the 
now established fact that matter of a nature common to that of the earth, 
and subject to laws similar to those which prevail upon the earth, exists 
throughout the stellar universe. 
The peculiar importance of Kirchhoff’s discovery to astronomy becomes 
obvious, if we consider the position in which we stand to the heavenly bodies. 
Gravitation and the laws of our being do not permit us to leave the earth, it 
is therefore by means of light alone that we can obtain any knowledge of the 
grand array of worlds which surround us in cosmical space. The star-lit 
heavens is the only chart of the universe we have, and in this luminous 
chart each twinkling point is the sign of an immensely vast, though distant 
region of activity. 
Hitherto the light from the heavenly bodies, even when collected by the 
largest telescopes, has conveyed to us but very meagre information, and in 
some cases only of their form, their size, and their colour. The discovery of 
Kirchhoff enables us to interpret symbols and indications hidden within the 
light itself, which furnish trustworthy information of the chemical, and also 
to some extent of the physical condition of the excessively remote bodies 
from which the light has emanated. 
Newton found that when white light is made to pass through a prism of 
glass it is decomposed into the beautiful colours which are seen in the rain- 
bow. ‘These colours, when they are in this way separated from each other, 
form the Spectrum of the light. 
About a century later Wollaston and Fraunhofer made the discovery that 
when the light of the sun is decomposed by a prism, the rainbow colours 
which form its spectrum are not continuous, but are interrupted by a large 
number of dark lines. These lines of darkness are the symbols which indi- 
cate the chemical constitution of the sun. It was not until recently, in the 
year 1859, that Kirchhoff taught us the true nature of these lines. He him- 
self immediately applied his method of interpretation to the dark lines of the 
* Communicated by the lecturer in conformity with a Resolution of the General Com- 
mittee at Norwich, 1868. 
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