A NEW ASTRONOMY 207 



mason work. To this pillar the quadrant was fixed in a vertical 

 plane, and steps were prepared to elevate the observer, when stars of 

 a low altitude required his attention. As the instrument could not 

 be conveniently covered with a roof, it was protected from the weather 

 by a covering made of skins; but notwithstanding this and other 

 precautions, it was broken to pieces by a violent storm, after having 

 remained uninjured for the space of five years. Brewster. 



A smaller but more serviceable azimuth quadrant of brass gave 

 angles to the nearest minute. He had a copper globe constructed 

 at great expense with the positions of some 1000 stars carefully 

 marked upon it. 



The very precision of his observations tended to confirm his 

 scepticism of the Copernican hypothesis, as it seemed incredible 

 that the earth's supposed orbital motion should cause no change 

 which he could detect in the position and brightness of the stars. 

 He was also misled by supposing that the stars had measurable 

 angular magnitude. He was not successful in making any funda- 

 mental improvement in the relatively crude methods of time 

 measurement, depending himself on wheel-mechanism without 

 the regulating pendulum, and an apparatus of the sand-glass or 

 clepsydra type. 



In 1577 Tycho made observations on a brilliant comet, and 

 drew from them important theoretical inferences; namely, that 

 instead of being an atmospheric phenomenon, the comet was at 

 least three times as remote as the moon, and that it was revolving 

 about the sun at a greater distance than Venus - - unimpeded by 

 the familiar crystalline spheres. He was even led, in discussing 

 apparent irregularities of its motion, to suggest that its orbit 

 might be oval foreshadowing one of Kepler's great discoveries. 



According to the current view of his time, comets 



were formed by the ascending from the earth of human sins and 

 wickedness, formed into a kind of gas, and ignited by the anger of 

 God. This poisonous stuff falls down again on people's heads, and 

 causes all kinds of mischief, such as pestilence, Frenchmen ( !), sudden 

 death, bad weather, etc. Dreyer, Tycho Brahe. 



