212 PROGRESS OF SCIENCE. 



astronomy, showed once more the unrivalled power of 

 mathematics in science. Leverrier rendered a much greater 

 service to astronomy. From 1838 to 1874 he worked out 



the ANALYSIS OF THE ORBITS OF THE PLANETS, by observing 



and calculating all the movements of the eight large planets. 

 This vast work the greatest accomplished in mathematical 

 astronomy in our time includes a determination of the 

 masses, disturbances and their causes, the interaction of 

 planets upon one another, so that it constitutes a table which 

 will enable future astronomers to ascertain within the next 

 2,000 years whether the same order, or a different order, 

 obtains. All this was again accomplished by the masterful 

 handling of mathematics the queen of sciences. 



1 8 . Schiaparelli revealed a NEW FEATURE in the con- 

 stitution of the heavenly bodies. He showed in 1862 that 

 the SWARM OF METEORS of August Qth to nth (that is, 

 the shooting stars called the Perseids) travelled in exactly 

 the SAME ORBIT AS THE COMET which appeared in that 

 year. This was the first time a meteoric orbit was de- 

 termined. The (i3th) November swarm (the Leonids) was 

 next traced out by Leverrier and Adams, the latter calcu- 

 lating it to travel beyond Uranus; and in 1866, a comet 

 was seen to move along precisely the same orbit. Adams's 

 masterly calculations proved the cycle of these November 

 meteoroids to be no less than 33^ years. Since then, 

 meteor swarms have been studied with great care, and an 

 immense number of them, describing rings more or less 

 regular, have been discovered, notably by Schiaparelli, 

 Proctor, and Prof. Newton. It is now ascertained that the 

 earth crosses every year the orbits of the August and 

 November meteoroids, and the meteorites which are met 

 by the earth are ignited by the friction of our atmosphere 

 and dissolved in their course through it, thus causing the 

 phenomenon known as shooting or falling stars. As there 

 are eighteen meteor showers every year, it is concluded that 

 we pass across the orbits of eighteen systems. According 

 to Prof. Newton and Schiaparelli, the August meteoroids 

 are nothing but the continuation of the 1862 comet, whose 

 tail is elongated all along the course of the comet's orbit. 



