SCIENCE IN THE LAST HALF CENTURY. 65 



half century, I may be thought to have exhibited more courage than 

 discretion, and perhaps more presumption than either. So far as phys- 

 ical science is concerned, the days of Admirable Crichtons have long 

 been over, and the most indefatigable of hard workers may think he 

 has done well if he has mastered one of its minor subdivisions. Never- 

 theless, it is possible for any one who has familiarized himself with the 

 operations of science in one department, to comprehend the significance, 

 and even to form a general estimate of the value, of the achievements 

 of specialists in other departments. 



Nor is there any lack either of guidance, or of aids to ignorance. By 

 a happy chance, the first edition of Whewell's " History of the Induc- 

 tive Sciences" was published in 1837, and it affords a very useful view 

 of the state of things at the commencement of the Victorian epoch. As 

 to subsequent events, there are numerous excellent summaries of the 

 progress of various branches of science, especially up to 1881, which 

 was the jubilee year of the British Association.* And, with respect to 

 the biological sciences, with some parts of which my studies have fa- 

 miliarized me, my personal experience nearly coincides with the pre- 

 ceding half century. I may hope therefore that my chance of escap- 

 ing serious errors is as good as that of any one else who might have 

 been persuaded to undertake the somewhat perilous enterprise in which 

 I find myself engaged. 



There is yet another prefatory remark which it seems desirable I 

 should make. It is that I think it proper to confine myself to the work 

 done, without saying anything about the doers of it. Meddling with 

 questions of merit and priority is a thorny business at the best of times, 

 and, unless in case of necessity, altogether undesirable when one is 

 dealing with contemporaries. No such necessity lies upon me; and 

 I shall therefore mention no names of living men, lest perchance I 

 should incur the reproof which the Israelites, who struggled with one 

 another in the field, addressed to Moses, ''Who made thee a i^rince and 

 a judge over us!" 



AIM OF FHYSICAL SCIENCE. 



Physical science is one and indivisible. Although for practical pur- 

 poses it is convenient to mark it out into the primary regions of Phys- 

 ics Chemistry, and Biology, and to subdivide these into subordinate 

 provinces, yet the method of investigation and the ultimate object of 

 the physical inquirer are everywhere the same. 



The object is the discovery of the rational order which pervades the 

 universe; the method consists of observation and experiment (which 

 is observation under artificial conditions) for the determination of the 



* I am particularly indebted to my fiUend and colleaRtie Professor Riicker, F. R. S., 

 for the many acute criticisms and sjiggostions on my remarks respcctinjj the ultimate 

 problems of physics, with which he has favored me, aud by which I have greatly 

 profited. 



H. Miss. 600 5 



