to8 PLEASANT WA YS IN SCIENCE. 



when they hear the word hypothesis, think immediately of 

 Newton's famous " hypotheses non fingo," a dictum relating 

 to real hypotheses, not to theories. It would, in fact, be 

 absurd to suppose that Newton, who had advanced, advo- 

 cated, and eventually established, the noblest scientific 

 theory the world has known, would ever have expressed an 

 objection to theorizing, as he is commonly understood to 

 have done by those who interpret his "hypotheses non 

 fingo " in the sense which finds favour with M. Coma But 

 apart from this, Newton definitely indicates what he means 

 by hypotheses. "I frame no hypotheses," he says, "for 

 whatever is not deduced from phenomena is to be called an 

 hypothesis" M. Cornu, it will be seen, rejects the idea of 

 deducing from phenomena what he calls an hypothesis, but 

 what would not be an hypothesis according to Newton's 

 definition : " Malgr tout ce qu'il y aurait de se"duisant et de 

 grandiose k tirer de ce fait des inductions, etc., je m'abstien- 

 drai de tout commentaire et de toute hypothese k ce sujet" 

 It is not thus that observed scientific facts are to be made 

 fruitful, nor thus that the points to which closer attention 

 must be given are to be ascertained 



Since the preceding paragraph was written, my attention 

 has been attracted to the words of another observer more 

 experienced than M. Cornu, who has not only expressed the 

 same opinion which I entertain respecting M. Cornu's ill- 

 advised remark, but has illustrated in a very practical way, 

 and in this very case, how science gains from commentary 

 and theory upon observed facts. Herr Vogel considers "that 

 the fear that an hypothesis " (he, also, means a theory here) 

 " might do harm to science is only justifiable in very rare 

 cases : in most cases it will further science. In the first 

 place, it draws the attention of the observer to things 

 \\-hich but for the hypothesis might have been neglected. 

 Of course if the observer is so strongly influenced that in 

 favour of an hypothesis he sees things which do not exist 

 and this may happen sometimes science may for a while 

 be arrested in its progress, but in that case the observer is 



