4 ON THE RELATION OF 



not merely is the number of the elements far greater, the 

 methods of producing complicated combinations of them 

 have been so vastly improved, that what is called organic 

 chemistry, which embraces only compounds of carbon with 

 oxygen, hydrogen, nitrogen, and a few other elements, has 

 already taken rank as an independent science. 



' As the stars of heaven for multitude ' was in ancient 

 times the natural expression for a number beyond our 

 comprehension, Pliny even thinks it almost presumption 

 (' rem etiam Deo improbam ') on the part of Hipparchus 

 to have undertaken to count the stars and to determine 

 their relative positions. And yet none of the catalogues 

 up to the seventeenth century, constructed without the 

 aid of telescopes, give more than from 1,000 to 1,500 

 stars of magnitudes from the first to the fifth. At pre- 

 sent several observatories are eno^aged in continuino- these 

 catalogues down to stars of the tenth magnitude. So 

 that upwards of 200,000 fixed stars are to be catalogued 

 and their places accurately determined. The immediate 

 result of these observations has been the discovery of a 

 great number of new planets ; so that, instead of the six 

 known in 1781, there are now seventy-five.^ 



The contemplation of tins astounding activity in all 

 branches of science may well make us stand aghast at 

 the audacity of man, and exclaim with the Chorus in the 

 'Antigone': 'Who can survey the whole field of know- 

 ledge ? Who can grasp the clues, and then thread the 

 labyrinth?' One obvious consequence of this vast exten- 

 sion of the limits of science is, that every student is 

 forced to choose a narrower and narrower field for his own 

 studies, and can only keep up an imperfect acquaintance 

 even with allied fields of research. It almost raises a 

 smile to hear that in the seventeenth century Kepler was 



' At the end of November 1864, the 82nd of the small planets, Alcmene, 

 was discovered. There are now 109. 



