34 A CENTURY'S PROGRESS IN ASTRONOMY. 



was a grand conception, and a magnificent attack 

 on the secrets of nature. 



Sir E/obert Ball says : " Not from abstract 

 speculation like Kant, nor from mathematical 

 suggestion like Laplace, but from accurate and 

 laborious study of the heavens, was the great 

 William Herschel led to the conception of the 

 nebular theory of evolution." Herschel's nebular 

 theory was wider and less rigorous than that 

 of Laplace. Laplace reached his theory by 

 reasoning backwards ; Herschel by observing the 

 nebulae in process of condensation. Consequently, 

 while Laplace's theory has required modification, 

 Herschel's, from its width, is universally ac- 

 cepted, because there is nothing mathematically 

 rigorous in it. The great German did not go 

 into details like his French contemporary. He 

 sketched the evolution of the stars in a wider 

 sense. 



The astronomer's " 1500 universes," Miss Clerke 

 remarks, " had now logically ceased to exist." 

 Herschel had gathered much evidence about 

 nebular distribution which shattered his belief 

 in external universes, although he still thought 

 in 1818 that some galaxies were included among 

 the non- gaseous nebulae. In 1784 Herschel 

 pointed out that the clusters and nebulae " are 

 arranged to run in strata " ; and some time later 



