September 15, 1911] 



SCIENCE 



337 



made, the effect observed may be due to the 

 direction of the current : and when a meas- 

 ured spectrum photograph is turned round 

 and remeasured, it is an admission of the 

 hypothesis that the direction of measure- 

 ment may be partly responsible for the ob- 

 served displacements of the spectrum lines. 

 By the various reversals we endeavor, in 

 Professor Chamberlin's words, "to bring 

 up into view every rational explanation of 

 the phenomenon in hand" which can be 

 brought up into view in this way. But 

 truly "no good thing is without its draw- 

 backs," and one drawback to the recogni- 

 tion of this principle is that, by a process 

 of mental confusion, it seems sometimes to 

 be regarded as a distinct merit in a piece 

 of apparatus that it can be reversed in a 

 large number of ways. It must be remem- 

 bered that the hypotheses thus examined 

 and ruled out are chiefly instrumental ones 

 superadded to those of nature : and the lat- 

 ter are already sufficiently numerous, with- 

 out our ingenious additions. 



The view which I have endeavored to 

 put before you of the inevitable course of 

 scientific work is that it will depend more 

 and more on the patient process of "leav- 

 ing no stone unturned. ' ' It may not be an 

 inspiring view, but it should be at least 

 encouraging, for it follows that no good 

 honest work is thrown away. And it is just 

 this encouragement of which the observer, 

 as opposed to the worker in the laboratory 

 and the mathematician, stands sometimes 

 in sore need. The worker in the labora- 

 tory can often clear away his hypotheses 

 on the spot : he can reverse his current then 

 and there : but this is often impossible for 

 the observer, who can and does reverse his 

 spectrum plate for measurement, but to 

 reverse the motion of the earth which af- 

 fected the lines must wait six months : and 

 to reverse also the motion of the star may 

 have to wait six years, or sixty, or sixty 



thousand. In many cases he must leave 

 the reversal to others, and thus not only 

 can he not test all his hypotheses, but he 

 may not even be able to formulate them. 

 His aim can not, therefore, be to establish 

 within his lifetime some new law, and his 

 work is not, therefore, to be appreciated or 

 condemned by his success or failure in this 

 respect. There are truer aims and surer 

 methods of judgment. Something is in- 

 evitably lost when we endeavor to express 

 these aims in the concrete ; but for the sake 

 of illustration we may say that the true 

 observer is always endeavoring to reach the 

 next decimal place, and is ever on the alert 

 for some new event. Of the pursuit of the 

 next decimal place it is needless to say 

 more : the aim is as familiar in the labora- 

 tory as in the observatory. But I often 

 think that the recognition of new events is 

 scarcely given its proper place in the an- 

 nals of science, if we have due regard to 

 the consequences. I have protested that in 

 much of his work the observer can not be 

 judged by the fruits of his labor, though 

 there is an instinctive tendency to judge in 

 this way : but here is a case where he might 

 well be content to be so judged, and yet the 

 consistent award is withheld. Think for a 

 moment of the very considerable additions 

 to our knowledge which have accrued from 

 the discovery by Professor W. H. Picker- 

 ing of an eighth satellite to Saturn. The 

 discovery led directly to the recognition of 

 the retrograde motion ; and to explain this 

 we were led to revise completely our views 

 of the past history of the solar system. 

 Incidentally it stimulated the search for 

 other new satellites, resulting in the dis- 

 covery of a curious pair to Jupiter and 

 next of the extraordinary eighth satellite; 

 while it was the investigation of the orbit 

 of this curiosity which suggested an emi- 

 nently successful method of work on com- 

 etary orbits. If we judge scientific work 



