320 AIM AND PROGRESS OF PHYSICAL SCIENCE. 



logian or historian, to seek out and search through books and 

 gather from them what others have already determined about 

 the subject under inquiry ; that is but a secondary portion of 

 our work. We have to attack the things themselves, and in 

 doing so each offers new and peculiar difficulties of a kind quite 

 different from those the scholar encounters ; while in the ma- 

 jority of instances, most of our time and labour is consumed by 

 secondary matters that are but remotely connected with the 

 purpose of the investigation. 



At one time, we have to study the errors of our instru- 

 ments, with a view to their diminution, or, where they cannot 

 be removed, to compass their detrimental influence ; while at 

 other times we have to watch for the moment when an organism 

 presents itself under circumstances most favourable for research. 

 Again, in the course of our investigation we learn for the first 

 time of possible errors which vitiate the result, or perhaps 

 merely raise a suspicion that it may be vitiated, and we find 

 ourselves compelled to begin the work anew, till every shadow 

 of doubt is removed. And it is only when the observer takes 

 such a grip of the subject, so fixes all his thoughts and all his 

 interest upon it that he cannot separate himself from it for 

 weeks, for months, even for years, cannot force himself away 

 from it, in short, till he has mastered every detail, and feels 

 assured of all those results which must come in time, that a 

 perfect and valuable piece of work is done. You are all aware 

 that in every good research, the preparation, the secondary 

 operations, the control of possible errors, and especially in the 

 separation of the results attainable in the time from those that 

 cannot be attained, consume far more time than is really required to 

 make actual observations or experiments. How much more 

 ingenuity and thought are expended in bringing a refractory 

 piece of brass or glass into subjection, than in sketching out the 

 plan of the whole investigation ! Each of you will have ex- 

 perienced such impatience and over-excitement during work 

 where all the thoughts are directed on a narrow range of 

 questions, the import of which to an outsider appears trifling 

 and contemptible because he does not see the end to which the 



