30 



SCIENCE 



[Vol. LV, No. 1411 



preparation begin observing, or whether he 

 shall consider that his conditions are not yet 

 favorable for exact work. Likewise the ques- 

 tion may come up in any long series of ob- 

 servations: When is it better to stop and try 

 to improve things rather than to go on in a 

 routine? A similar choice may come to an 

 individual even in deciding his preference for 

 one science or another, and in the fundamental 

 sense this same choice runs through much of 

 our lives, the attraction of the old versus the 

 new. 



While we may take up certain considerations 

 from the limited point of view of astronomers, 

 there are undoubtedly applications of these 

 same ideas in many fields of science. Of 

 course we are all interested in improvements, 

 and no one of us would care to admit that he 

 has not the patience and concentration to keep 

 at a task until he has mastered it and can do 

 it well. There are, however, differences in indi- 

 viduals, and as time goes on these are accen- 

 tuated, and each worker naturally tends to 

 gravitate into the field where he works best 

 and feels at home. The skillful observer is 

 usually an orderly person who keeps his sur- 

 roundings and apparatus neat and tidy. His 

 instinct is to maintain constant conditions, 

 and if his instrument or apparatus is working 

 perfectly, to let everything remains undistui-bed. 

 There is good reason for this, since experience 

 often shows that variation of conditions intro- 

 duces unsuspected errors. The experimenter, 

 on the other hand, seems to take delight in 

 being surrounded by the debris of his work. 

 Order and system are not part of his creed. 

 He has no hesitancy in dissecting any fine new 

 instrimient if some of its pieces will fit in with 

 what he wants, probably much to the consterna- 

 tion of his colleague who is responsible for the 

 equipment. Whenever the observer sees or does 

 anything, he writes down a note, but writing is 

 the last thing of which the experimenter 

 thinks. The observer takes apparatus as it 

 ■comes to him, the experimenter improves ap- 

 paratus or devises something new. The ob- 

 server keeps all or almost all his work, the 

 experimenter has no scruples in throwing away 

 anything which he thi nks he can improve upon. 



I remember visiting a laboratory in company 



with a prominent astronomer, where we were 

 shown some spectrum photographs. The 

 physicist in charge showed us a negative which 

 he had just taken, and then threw it aside. My 

 companion promptly asked if there could not 

 be something of value on that plate, if it 

 should not be kept. The experimenter an- 

 swered that he had dozens equally poor, and 

 that he could reproduce it at will. To the 

 observer even a poor photograph may repre- 

 sent an opportunity which will never return. 



It is much easier to teach large classes of 

 students to observe, after a fashion, than to 

 experiment. In a laboratory section, the stu- 

 dent will consider favorably a system which 

 enables him to come in and sit down at his 

 table, and without delay to begin and simply 

 take readings. We hear a great deal about 

 teaching the scientific method, but it would be 

 quite impracticable to inflict upon elementary 

 students the real methods of science, the trials 

 and waste of time which any one must undergo 

 before he can determine what he needs, and 

 then find and assemble his apparatus. 



There is one dii-ection in which an observer 

 sometimes feels that he has the advantage over 

 the experimenter, and that is in this matter of 

 waste of time. An hour's work for the ob- 

 server brings an hour's results, whereas the 

 experimenter often puts in a great deal of 

 effort with apparently no return. A safe pro- 

 gram of observation brings in sure returns; 

 but is not any one mistaken in assuming that 

 he can avoid waste of effort? It is the fate of 

 most scientific work to be superseded, and the 

 most accurate observations are likely to be 

 quite out of date even in the lifetime of an 

 individual. Bradley's star places have been 

 and are still of great importance as a basis for 

 proper motions of stars, but the time will come 

 when the so-called modern observations will be 

 of the same order of antiquity as those of a 

 century and a half ago, and Bradley's obsei-va- 

 tions will gradually lose their importance. On 

 the other hand, there are many results from 

 positions and proper motions of stars deter- 

 mined from current measures which are obvi- 

 ously of permanent value. Such a case is 

 Boss's cluster in Taurus, a group of stars now 

 widely dispersed, but which as time goes on 



