316 TRANSACTIONS OF SECTION A. 



Then I found 3 that the day and the year were correlated, the value of the 

 coefficient being 



r = O56±0 08. 



Having obtained this clue it was interesting to use it for the elucidation of 

 individual problems. The days of many stars are by this time pretty well known, 

 but their years are very uncertain. In nine or ten cases the assessment of the 

 vaguely known year was under revision, and in all, without exception, the revised 

 assessment tended in the direction of the formula. In one case (S Serpentis) 

 the formula suggested the solution of a long-standing puzzle. 1 Finally the inquiry 

 is suggested whether our own sun may be treated as a variable star with a period 

 or day of eleven years, in which case its tune of swing a year should be about 

 seventy-five years, if the formula is strictly linear. There are found to be indica- 

 tions of a swing of this order of magnitude, though the time given by the 

 periodogram method is fifty-four years. 5 If the relation between year and day 

 is not strictly linear these figures could easily be reconciled for a case lying so 

 far outside the limits within which the formula was deduced. But the ultimate 

 successful establishment of the connection is of less importance for our present 

 purpose than to notice the fruitfulness of the method of suggestion, which is as 

 mechanical as Bacon himself could have wished. 



Let us admit frankly that there is an appearance of brutality about such 

 methods. Is our method of search to be merely the old and prosaic one of leaving 

 no stone unturned ? We have been led to believe that there should be more of 

 inspiration in it; that a true man of science should have some of the qualities 

 of that fascinating hero of fiction, Mr. Sherlock Holmes, who picks up his clue 

 and follows it unerringly to the triumphant conclusion. Such qualities will do 

 the man of science no possible harm : indeed they will be of the utmost value to 

 him. The point to which I am now calling attention is the change in nature of 

 the opportunities for using them, which are becoming every day more confused. 

 Sir Conan Doyle, in the exercise of his art, keeps our attention fixed on a single 

 trail : he conceals from us by mere omission the numerous trails which cross it. 

 We admire the skill of the Indian who pursues an enemy through the trackless 

 forest : but his success depends on the simplicity brought by this very trackless- 

 ness, and would be imperilled if there were numerous tracks. It may be remarked, 

 however, that there is a still higher sagacity — that of the hound who even among 

 a number of tracks can pick out the right one by scent. Let us imagine for a 

 moment that the scientific man can be endowed in the future, by training or by 

 some new invention, with a faculty of this kind, so that he may unerringly pursue 

 a single trail even when it is crossed and recrossed by others. Then in the terms 

 of this metaphor I draw attention to the fact that he has still to determine which 

 is the right trail; and that in general he can only do so by pursuing each in 

 turn to the end. To take an example from recent scientific anecdote : I relate 

 the story as I was told it, and even if incorrect in detail it will serve its purpose 

 as a parable. The Rontgen rays were discovered originally by their photographic 

 action, but afterwards it was found that they would render a screen of calcium 

 tungstate phosphorescent. I was told that this discovery had been made in this 

 wise : Mr. Edison had a large collection of different chemicals, and a number of 

 assistants: he set his assistants busily to work to try each substance in turn until 

 the right one was found. Now this is not only a genuine scientific process, but it 

 is the fundamental process. Let it be frankly admitted that our instincts are 

 against it. We should much prefer to hear that some hypothesis had pointed the 

 way, even a false hypothesis such as actually led to the discovery of the possi- 

 bility of achromatism in lenses. Or if memory had played a part : The other 

 day Professor Fowler identified the spectrum of a comet's tail with one taken in 

 his laboratory, of which he had some recollection, and our human sympathies 

 fasten at once on this idea of recollection as a praiseworthy element in the dis- 

 covery. Nay, even mere accident appeals to us more than brutal industry : if 

 Mr. Edison had wandered into his laboratory, picked up a bottle at random, 

 and found it answer his purpose, I venture to say that we should have instinc- 

 tively awarded him more merit : there would have been just a chance that he was 



3 Monthly Notices B.A.S., lxviii., p. 541. 

 ' Ibid., lxviii., p. 561. 5 Ibid., p. 659. 



