DISCOVERIES IN THE CELESTIAL SPACES. 351 



tven ventured to determine numerically the amount of this 

 compression, on the assumption of the homogeneous nature of 

 the mass. It remained for the comparative measurements of 

 degrees in the eighteenth and nineteenth centuries, at the 

 equator, near the north pole, and in the temperate zones of 

 lioth the southern and northern hemispheres, to determine 

 exactly the mean amount of this compression, and by that 

 means to ascertain the true figure of the Earth. The exist- 

 ence of this compression announces, as has already been ob- 

 served in the " Picture of Nature,"* that which may be nam- 

 ed the most ancient of all geognostic events — the condition of 

 general fluidity of a planet, and its earlier and progressive so- 

 lidification. 



We began our description of the great epoch of Galileo, 

 Kepler, Newton, and Leibnitz with the discoveries in the re- 

 gions of space by means of the newly-invented telescope, and 

 we now close it with the figure of the Earth, as it was then 

 recognized from theoretical conclusions. " Newton was ena- 

 bled to give an explanation of the system of the universe be- 

 cause he succeeded in discovering the forcef from whose action 

 the laws of Kepler necessarily result, and which most corre- 

 spond with these phenomena, since these laws corresponded to 

 and predicted them." The discovery of such a force, the ex- 

 istence of which Newton has developed in his immortal work, 

 the JP?'i?icipia (which comprise the general sciences of nature), 

 was almost simultaneous with the opening of the new paths to 

 greater mathematical discoveries by means of the invention of 

 the infinitesimal calculus. Intellectual labor shows itself in 

 all its exalted grandeur where, instead of requiring external 

 material means, it derives its light exclusively from the sources 

 opened to pure abstraction by the mathematical development 

 of thought. There dwells an irresistible charm, venerated by 

 all antiquity, in the contemplation of matViematical truths — 

 m the everlasting revelations of time and space, as they reveal 



* Cosmos, vol. i., p. 163. The dispute regarding priority as to the 

 knowledge of the Earth's compression, in reference to a memoir read 

 by Huygens in 1669 before the Paris Academy, was first cleared up by 

 Delambre in his Hisl. de VAstr. Mod., t. i., p. lii., and t. ii., p. 558. 

 Richer's return to Europe occurred indeed in 1673, but his work was 

 not printed until 1679; and as Huygens left Paris in 1682, he did not 

 write the Additamentum to the Memoir of 1669, the publication of which 

 was very late, until he had already before his eyes the results of Rich- 

 er's Pendulum Experiments, and of Newton's great work, Philosophia 

 Naturalis Principia Mathematica. 



t Bessel. in Schumacher'' s Jahrbuch fUr 1843, s. 32. 



