PRESIDENTIAL ADDRESS 309 



Even if the like has never happened before, this scientific advance is at any rate 

 due to little more than the accumulation of facta which arranged themselves, as 

 Bacon hoped would naturally happen. But does it detract from the merits of 

 this fine piece of observational work that it was suggested by no leading theory ? 

 And I will ask even further : Would its merits have been less if no such imme- 

 diate induction had presented itself? To this second question I can scarcely 

 expect a general answer in the affirmative; it is so natural to judge by results, 

 and so difficult to look beyond them to the merits of the work itself that I shall 

 not easily carry others with me in claiming that the merits of the observer shall 

 be assessed independently of his results. And yet I affirm unhesitatingly that 

 until this attitude is reached, we cannot do justice to the observer. I believe 

 it will be reached in the future, and I shall endeavour to give reasons for this 

 forecast; but I admit frankly that our habit of judging by results will be hard 

 to break. It extends even to the observer himself, and leads to the withholding 

 of his observations from publication, so that he may himself extract the results 

 from them. In the pure interests of the advance of knowledge, it would be far 

 better to publish the material, so that many brains rather than one might work 

 upon it. But the observer knows that by this course he risks losing almost the 

 whole value of his patient work, which would pass as unearned increment to 

 the particular person who was lucky enough to make the induction. Hence arise 

 quarrels such as those between Flamsteed and Newton; the former refusing to 

 publish his observations until he had himself had an opportunity of discussing 

 them, while Newton and Halley exerted their powerful influence in the contrary 

 sense. This situation by no means belongs to a bygone age; it may and does 

 arise to-day, and will continue to arise so long as the recognition of the observer's 

 work is inadequate. It was mentioned a few minutes ago that Mr. Campbell had 

 incurred adverse criticism by accumulating a considerable mass of unpublished 

 observations. Let me be careful not to suggest that his primary motive was 

 the desire to have the first use of them, for I happen to know that there was at 

 least one other good and sufficient reason for his action in the difficulty of find- 

 ing funds for publication, a difficulty with which observers are only too familiar. 

 But, whatever the reason, there were those who regretted the delay in publica- 

 tion as hindering the advance of science. The whole question is a delicate one, 

 and might have been better left unraised at the moment but for a most curious 

 sequel, which puts clearly in evidence the importance of the observer and the 

 desirability of allowing him to discuss his own work. To make this clear a 

 small digression is necessary. 



During the last half-dozen years astronomers have been startled on several 

 occasions by pieces of news of a particular kind, indicating the association of 

 large, widely scattered groups of stars in a common movement. The discussion 

 of these movements is to occupy the special attention of this Section at one of our 

 meetings, which is an additional reason for brevity in the present allusion. Pos- 

 sibly also most members of the Section have already heard of Professor 

 Kapteyn's division of the great mass of bright stars into two distinct groups 

 flying one through the other; and again of the discovery by Professor Boss of 

 a special cluster of stars in the constellation Taurus, moving in parallel lines 

 like a flock of migrating birds. The fascination of this latter discovery, and of 

 one or two others like it, is that when the information supplied by the spectro- 

 scope is combined with that furnished by the long watching of patient observers, 

 we can determine the distance of the cluster and its shape and dimensions. We 

 realise, for instance, that there is a large flat cluster migrating just over our 

 heads, so that one member of it (Sirius) is close to our Sun — that is to say, only 

 nine or ten light-years from him. ' Close ' is a relative term ; and the distance 

 travelled by light in three years is from some standpoints by no means despicable. 

 But it is small in comparison with the dimensions of the cluster, which is about 

 one hundred light-years from end to end. The study of these clusters will 

 doubtless occupy our close attention in the immediate future ; and it is very 

 natural that the discovery of one should lead to the search for others. Accord- 

 ingly we heard last autumn with the deepest interest, but with modified sur- 

 prise, the announcement of common movement in a class of stars of a particular 

 spectral type. The announcement rested to some extent on the work done at 

 the Lick Observatory, much of which has been published in an abbreviated 



