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III* On the Nature and Construction of the Sun and fixed Stars. 
By William Herschel, LL.D. F. R. S. 
Read December 18, 1794. 
Among the celestial bodies the sun is certainly the first 
which should attract our notice. It is a fountain of light that 
illuminates the world ! it is the cause of that heat which main- 
tains the productive power of nature, and makes the earth a fit 
habitation for man ! it is the central body of the planetary 
system ; and what renders a knowledge of its nature still 
more interesting to us is, that the numberless stars which 
compose the universe, appear, by the strictest analogy, to be 
similar bodies. Their innate light is so intense, that it reaches 
the eye of the observer from the remotest regions of space, 
and forcibly claims his notice. 
Now, if we are convinced that an inquiry into the nature 
and properties of the sun is highly worthy of our notice, we 
may also with great satisfaction reflect on the considerable 
progress that has already been made in our knowledge of this 
eminent body. It would require a long detail to enumerate all 
the various discoveries which have been made on this subject ; 
I shall, therefore, content myself with giving only the most 
capital of them. 
Sir Isaac Newton has shewn that the sun, by its attractive 
power, retains the planets of our system in their orbits. He 
