io SCIENTIFIC METHOD 



Bacon justly called the new instrument the Novum 

 Organum. He was its discoverer. Baconian induction 

 is founded on the sound principle that things which in 

 experience are always present, absent, and varying 

 together, are universally connected. It is a principle 

 which is morally certain, without pretending to be mathe- 

 matically necessary. Once recognized, it passed' into 

 modern science and logic. Accordingly, we can trace 

 Bacon's three tables of presence, absence, and com- 

 parison, founded on it, through the writings of Boyle, 

 Keill, and Herschel, till finally they became the essence 

 of Mill's logic of induction under the titles of agreement, 

 difference, and concomitant variation l . 



The power of the empirical method can readily be 

 exemplified before as well as after the time of Bacon. 

 Astronomy, of all sciences, requires registered experi- 

 ence of many observations in series and periods. Bacon 

 had this precedent before him, and especially the observa- 

 tions of Tycho Brahe on the planet Mars. He knew 

 also of the discoveries of Galileo, first announced by the 

 discoverer in the Sidereus Nuncius (1610), and peculiarly 

 valuable as showing that experience and induction do 

 not require hypothesis. Having constructed his own 

 telescope, and directed it to the stars, Galileo found 

 (i) the roughness of the moon, so different from the 

 smooth sphere ordinarily supposed ; (2) the stars of 

 the Milky Way ; (3) the stars of which nebulae consist ; 

 and (4) most wonderful of all, the satellites of Jupiter, of 

 which he made a regular nightly register. Later, with 

 the same instrument, he discovered Saturn's ring and 



1 See Bacon, Novum Organum, ii, 10-20; Boyle, Experiments about 

 the Mechanical Origine of divers particular Qualities. Advertisements ; 

 Keill, Introductio ad veram Physicam, Lect. viii, Ax. 7 ; Herschel, Pre- 

 liminary Discourse on the Study of Natural Philosophy, 145; Mill's 

 Logic, Book iii, chap. 8. 



