Historical Relations 133 



function not of the period of fall but of the weight of the object. 

 Galileo's critical attitude to Aristotle, the bulwark of the scholastic 

 system, earned him the virulent enmity of the academic classes. 

 Immediately it cost him his chair. He had, however, made the 

 first definitive breach in the Aristotelian armour. 



The next twelve years, though fruitful in scientific discovery, 

 are not important for our theme. Galileo's work of 1604 was 

 more revolutionary. In that year a new star appeared in the con- 

 stellation Serpent arms. He demonstrated that this star was 

 without parallax and must inferentially be situated beyond the 

 planets and among the remote heavenly bodies. Now this remote 

 region was regarded in the Aristotelian scheme as absolutely 

 changeless. Although new stars had been previously noticed, 

 they had been considered to belong to the lower and less perfect 

 regions nearer to earth. To the same lower region, according to 

 the then current theory, belonged such temporary and rapidly 

 changing bodies as meteors and comets. Galileo had thus attacked 

 the incorruptible and unchangeable heavens. 



In 1609 Galileo made accessible two instruments that were 

 to have a deep influence on the subsequent development of science, 

 the telescope and microscope. The latter instrument he seldom 

 used. For long it was employed almost exclusively by biologists, 

 and Galileo was no biologist. It is with the former instrument 

 that his name is most frequently associated. His first discoveries 

 made by means of the telescope were issued in i6jo. That year 

 was crowded with important observations which we may consider 

 briefly. 



The first yield of the telescope was an immense number of 

 hitherto unobserved fixed stars. It was soon found that these 

 were at least ten times as numerous as those that had been cata- 

 logued. The more conspicuous star clusters were found to contain 

 many stars too faint for recognition by the naked eye. Parts of 

 the milky way and some of the nebulous patches were resolved into 

 congeries of stars of various magnitudes. The surface of the moon, 

 so far from being smooth and polished, was " very similar to the 

 earth," rough with depressions and high mountains. The height 

 of the lunar mountains was even measured by means of the shadows 

 that they cast. The four satellites of Jupiter were discovered. 

 The comparison of their movements to that of our moon suggested 

 resemblances of our earth to the planet Jupiter. The outermost 



