4 ON THK RELATION OF 



1,000 to 1,500 stars of magnitudes from the first to the fifth. 

 At present several observatories are engaged in continuing these 

 catalogues down to stars of the tenth magnitude ; so that up- 

 wards of 200,000 fixed stars are to be catalogued and their places 

 accurately determined. The immediate result of these obser- 

 vations 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. 1 



The contemplation of this 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 knowledge 1 Who can grasp the 

 clues, and then thread the labyrinth 1 ' One obvious consequence 

 of this vast extension 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 invited to 

 Gratz as professor of mathematics and moral philosophy : and 

 that at Leyden, in the beginning of the eighteenth, Boerhave 

 occupied at the same time the chairs of botany, chemistry, and 

 clinical medicine, and therefore practically that of pharmacy as 

 well. At present we require at least four professors, or, in an 

 university with its full complement of teachers, seven or eight, 

 to represent all these branches of science. And the same is 

 true of other faculties. 



One of my strongest motives for discussing to-day the con- 

 nection of the different sciences is that I am myself a student 

 of natural philosophy; and that it has been made of late a 

 reproach against natural philosophy that it has struck out a 

 path of its own, and has separated itself more and more widely 

 from the other sciences which are united by common philological 

 and historical studies. This opposition has, in fact, been long 

 apparent, and seems to me to have grown up mainly under the 

 influence of the Hegelian philosophy, or, at any rate, to have 



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

 discovered. There are now 109. 



