290 



NATURE 



[August 31, 191 1 



in the shape of laws, on pain uf being classed as an inferior 

 1 in the social scientific scale, he would have been lament- 

 ably unprepared. Or consider the case of M. Teisserenc 

 do Bort, when he began sending up his balloons. " Show 

 me your laws," cries the mathematician. " But they are 

 just what 1 hope to find," replies M. de Bort. "Yes, 

 but surely you have formulated some law you wish to 

 test?" pursues the invigilator. "How am 1 to giv you 

 proper scientific rank unless you can produce at least a 

 tentative law?" "On the other hand I wish to keep a 

 perfectly open mind," maintains M. de Bort. " Then I 

 fear 1 cannot admit you to our class at present ; you must 

 join the infants' class, and 1 can only give you my best 

 wishes that you may reach maturity some day." Unper- 

 turbed, M. de Bort continues to send up his balloons, and 

 almost immediately discovers the great fact about the 

 isothermal region which will be a permanent factor in the 

 meteorology of the future. The mathematician is now 

 ready to admit him, as a worthy person who has found 

 a law about the constitution of the atmosphere. But was 

 not the merit in sending up the balloons, whatever came 

 of it? Is it not sometimes more courageous to take risks 

 of failure? The mathematician, safe in his stronghold 

 which possesses " probably in the highest degree attain- 

 able by the human intellect the characteristics of perfect 

 and necessary science," is like a man who has inherited 

 a good old-established business, and he has a distaste for 

 the methods of those who have to try new ventures. No 

 doubt many who make such trials fail ; but, on the other 

 hand, great fortunes have been made in that way. 



It may seem, however, that too much is being deduced 

 from a single quoted opinion, which may easily have been 

 personal and not representative. Let me, therefore, take 

 another which presents a different aspect of the same 

 matter. I take the opening words of Sir G. H. Darwin's 

 Address to this Section at Birmingham in 1886. 



" A mere catalogue of facts, however well arranged, 

 has never led to any important scientific generalisation. 

 For in any subjects the facts are so numerous and many- 

 sided that they only lead us to a conclusion when they are 

 marshalled by the light of some leading idea. A theory is 

 then a necessity for the advance of science, and we may 

 regard it as the branch of a living tree, of which facts 

 are the nourishment." 



Those who have read the letters of Charles Darwin will 

 recognise that this opinion was also held by the father, 

 and may have been adopted by the son. It is no part of 

 my purpose to raise any question of originality : I mention 

 the point merely to take the opportunity it gives me of 

 showing that 1 do not approach lightly an opinion held 

 by two such men. With the utmost respect, I wish to 

 question whether the criterion indicated goes deep enough. 

 Often have we had ocular demonstration of the value of 

 a theory in stimulating the advance of science ; but is 

 advance wholly dependent on the existence of a theory ? 

 I have tried to indicate already a deeper motive power 

 by such instances as the work of Tycho, who had no 

 theory, but who perceived the need of observation. And 

 I will now definitely formulate the view that the percep- 

 tion of the need for observations, the faith that something 

 will come of them, and the skill and energy to act on 

 that faith — that these qualities, all of which are possessed 

 by any observer worthy the name, have at least as much 

 to do with the advance of Science as the formulation of 

 a theory, even of a correct theory. The work of the 

 observer is often forgotten — it lies at the root of the plant ; 

 it is easier to notice the theories which blossom and ulti- 

 mately produce the fruit. But without the patient work 

 of the observer underground there would be neither blossom 

 nor fruit. It is also easy to fix attention on the mechanical 

 nature of much observation ; but this is not the principal 

 feature of observing any more than is numerical com- 

 putation of mathematics. There are men like Adams who 

 perform gigantic numerical computations faultlessly, but 

 there arr- other* who would take equal rank as mathe- 

 maticians who cannot do three additions correctly ; and. 

 again, others who could compute well and quickly, but 

 prefer to hand over that part of their work to someone 

 Similarly some great observers themselves look 

 through the telescope, and some merely direct others how 

 to do so ; the spark of divine fire is not dependent on this 



detail, but on the possession of the qualities above men- 

 tioned — perception, faith, skill, and energy. 



By way of bringing out more fully the nature of th& 

 assertion made by Sir George Darwin, let me beg your 

 attention to a striking incident in recent astronomical 

 history. We all know how the great astronomer we lost 

 last year, Sir William Muggins (.one of those already 

 mentioned as having occupied the presidential chair of the 

 Association without having filled that of Section A), 

 initiated the determination of velocities of the heavenly 

 bodies in the line ot sight by means of the spectroscope. 

 We know, further, how the accuracy of these determina- 

 tions was improved by the application of photography, so 

 that it has recently become possible to measure the velocity 

 of the earth in its orbit (as it alternately approaches anil 

 recedes from a given star) with a precision which matches 

 that of other known methods. Now Mr. W. W. Camp- 

 bell, on his appointment as Director of the Lick Observa- 

 tory in 1900, perceived the desirability of observing the 

 line-of-sight velocities of as many stars as possible, believed 

 that that outcome would be in some way for the advance- 

 ment of science, and resolutely acted on that belief, so 

 that for many years the resources of his great establish- 

 ment have been devoted to this work. He has not turned 

 aside from it even to publish provisional results, and has 

 thereby incurred some adverse criticism. But, having now 

 accumulated a large mass of observation, he is proceeding 

 to let them tell their own tale, and a wonderful story it 

 is. We have, unfortunately, not time to listen to more 

 than a fraction of it at the moment ; but that fraction is 

 well worthy of our attention. When the stars are grouped 

 in classes according to their spectral type, their average 

 velocities differ ; and if the spectral types are arranged in 

 that particular order which for quite independent reasons 

 we believe to be that of development of the stars, there is 

 a steady increase in the velocities. To put the matter in 

 a nutshell, the older a star is the quicker it moves. There 

 are no doubt several assumptions made in reducing the 

 matter to this simple statement, but I venture to think 

 that they do not affect the point I now wish to make, 

 which is as follows. There is no doubt whatever that the 

 catalogue of facts accumulated by Mr. Campbell, when 

 arranged in an obvious order, has led to a most important 

 scientific generalisation — a direct negative at this date of 

 Sir George Darwin's "opening sentence, however true it 

 may have been when he wrote it. If we read on, his next 

 sentence doubtless entitles him to say that it was the 

 marshalling of the facts which led to the conclusion. It 

 is not altogether clear to me in what way this marshalling 

 differs from the permitted " arrangement " of the cata- 

 logue ; but the third sentence seems to imply that the 

 distinction lies in the existence of a theory. But certainly 

 Mr. Campbell had no theory ; so far is he from having 

 had a theory that he finds it extremely difficult, if not at 

 present actually impossible, to formulate one which will 

 satisfactorily account for the extraordinary fact brought 

 to light by the simple arrangement of his catalogue. 



Witness his words in Lick Observatory " Bulletin." 

 No. iq6, dated April 20 last : — 



" The correct interpretation of the observed facts referred 

 to in this ' Bulletin ' seems not easy of accomplishment, 

 and the brief comments which follow make no pretensions 

 to the status of a solution. 



" That stellar velocities should be functions of spectral 

 types is one of the surprising results of recent studies in 

 stellar motions, for we naturally think of all matter as 

 equally old gravitationally. Why should not the materials 

 composing a nebula or a Class B star have been acted 

 upon as long and as effectively as the materials in a 

 Class M star? . . . The established fact of increasing 

 stellar velocities with increasing ages suggest the ques- 

 tions : Are stellar materials in the ante-stellar state subject 

 to Newton's law of gravitation? Do these materials exist 

 in forms so finely divided that repulsion under radiation 

 pressure more or less closely balances gravitational attrac- 

 tion ? Does gravity become effective only after the pro- 

 cesses of combination are well under way? " 



Mr. Campbell is far from being helpless in the situation 

 he has created : he is ready with suggestions, though he 

 modestly puts them as questions ; but they are obviously 

 consequent, and not antecedent, to the advance which 



NO. 2l! 



VOL. 



87] 



