374 LEADING AMERICAN MEN OF SCIENCE 



successful manner to elevate the level of the civilization of our age, 

 enriching the domain of science with beautiful and durable con- 

 quests." 



While a young man in Cambridge, Newcomb determined to 

 devote his life to the prosecution of exact astronomy, and the first 

 problem which he took up was that of the zone of those minor 

 planets, called asteroids, which revolve between the orbits of 

 Mars and Jupiter. This investigation, published in 1860, under 

 the title On the Secular Variations and Mutual Relations of the 

 Orbits of the Asteroids showed that the orbits of these bodies "had 

 never passed through any common point of intersection" and 

 hence were not fragments of a larger body that had met with some 

 catastrophe as had been generally believed. "The whole trend 

 of thought and research since that time," says Newcomb, "has 

 been towards the conclusion that no such cataclysm as that looked 

 for ever occurred, and that the group of smaller planets had been 

 composed of separate bodies since the solar system came into 

 existence." 



His own statement of "the great problem of exact astronomy" 

 to which he gave so much of his life and thought is as follows: 



" It is well known that we shall at least come very near the truth 

 when we say that the planets revolve around the sun, and the satel- 

 lites around their primaries according to the law of gravitation. 

 We may regard all these bodies as projected into space, and thus 

 moving according to laws similar to that which governs the motion 

 of a stone thrown from the hand. If two bodies alone were con- 

 cerned, say the sun and a planet, the orbit of the lesser around the 

 greater would be an ellipse, which would never change its form, 

 size, or position. That the orbits of the planets and asteroids do 

 change, and that they are not exact ellipses, is due to their attrac- 

 tion upon each other. The question is, do these mutual attrac- 

 tions completely explain all the motions down to the last degree of 

 refinement ? Does any world move otherwise than as it is attracted 

 by other worlds? 



"Two different lines of research must be brought to bear on the 

 question thus presented. We must first know by the most exact 

 land refined observations that the astronomer can make exactly 

 how a heavenly body does move. Its position, or, as we cannot 



